Japanese Language Maintenance for International School Students: Why "Speaking at Home Is Fine" Is a Warning Sign, and How to Approach Learning from the Goal of Age 18

"My child speaks Japanese naturally at home, so we should be fine."

Many families with children in international schools begin with this assumption. However, when you ask these children to read grade-level texts or write essays, you often discover they cannot write kanji as well as expected, or their written compositions lack coherence.

Conversely, some parents worry: "If we focus on Japanese, won't it hold back English progress?" Many families find themselves uncertain about which language to prioritize.

In this article, ELT—which has provided counseling to over 300 families—shares what actually happens with Japanese language development in international school students, and when, what, and to what extent families should focus on it, in the clearest way possible.

This article's conclusion: Attending an international school does not cause Japanese to disappear entirely. However, because students spend more time using English at school, the time spent "reading, writing, and thinking" in Japanese naturally decreases unless families are intentional about it. Even if conversation skills are strong, kanji, reading comprehension, and essay writing require separate development. The key is not to worry about "English or Japanese," but rather to decide first what you want your child to be able to do in Japanese by age 18, and work backward from that goal to determine what to do now.

1. What "Japanese Language Decline" Actually Means

Differences in international school students' Japanese typically appear first not in conversation, but in "academic Japanese"—kanji, reading comprehension, and essay writing. Because conversation skills remain strong, those around them often don't notice the gap until they see written work. This is a common pattern.

"Japanese language proficiency" encompasses several different skills.

There is conversation with family and friends, vocabulary, kanji, reading comprehension, essay writing, and the language used in academic contexts—such as explaining reasoning or summarizing key points. International school students maintain conversational skills through daily life. However, kanji, essay writing, and academic language are typically developed naturally through daily classroom instruction in Japanese schools. International school students have far fewer opportunities to practice these skills unless families are deliberate about providing them.

Research conducted at an international school in Tokyo confirmed that reading, writing, and kanji skills were weaker compared to speaking ability. The study also found that children who used Japanese frequently outside school had stronger essay-writing skills.

Ages 8 to 10: A Critical Turning Point

Gaps become most visible around upper elementary school (grades 3–4). In lower grades, if a child can use hiragana and everyday vocabulary, Japanese seems fine. However, by grades 3–4, Japanese textbooks introduce more challenging vocabulary such as "percentage," "common ground," and "cause," along with a sharp increase in logical explanations. Children who have not received Japanese instruction at school often show noticeable gaps compared to their grade-level peers at this stage.

There is no fixed number of years after entering international school when Japanese decline occurs. What matters more is whether the child continues to have experiences reading and writing in Japanese.

2. What We Learn from Inquiries at ELT

ELT frequently receives inquiries from parents of international school students about their children's lagging kanji, reading comprehension, and essay writing compared to grade-level peers. Because conversation poses no problem, the gap often widens before parents realize it exists.

ELT works with many students who attend international schools while receiving support in English and academics. From these families, we receive inquiries about Japanese language as frequently as we do about English.

The concerns almost always center on three areas: kanji, reading comprehension, and essay writing. Since daily conversation proceeds without difficulty, parents believe "Japanese is fine." However, when asked to read or write at grade level, they are surprised to discover their child's gap compared to same-age peers. This is the typical pattern of these inquiries.

When we receive such concerns, we first communicate two key points:

① Do not judge based on conversation ability. The starting point is to actually have your child read and write grade-level texts to see where they truly stand, rather than relying on how well they speak.

② It is entirely possible to catch up once a gap is identified. Even if a gap exists, there is no need to panic. By deciding "what" and "how far" to pursue based on your child's goals, you can make steady progress without unnecessary burden. We explain how to make this decision in Chapter 4.

3. Is It True That Developing Japanese Will Limit English Growth?

The concern that developing Japanese will limit English progress has no basis. In fact, the "reading ability" and "thinking skills" developed through Japanese serve as a foundation for learning in English.

Language research shows that "the ability to converse with peers" and "the ability to use a language for academic purposes" are distinct. Conversation develops relatively quickly, but academic language takes much longer to develop. This applies equally to both English and Japanese.

Another well-established principle is that "skills developed in a first language transfer to other languages." A child who has developed strong reading comprehension and logical thinking skills in Japanese can apply those same skills to English learning. The International Baccalaureate (IB) also emphasizes the importance of multiple languages as a core educational principle.

Four Common Misconceptions

4. Decide Your "Age 18 Goal" First, Then Work Backward

Japanese language planning should be based not on "whether it is maintained," but on "what you want your child to be able to do in Japanese by age 18." The amount of study required depends entirely on the goal, so there is no one-size-fits-all answer. ELT calls this approach "Planning Japanese Language from the Goal."

Some families are satisfied if their child can enjoy conversation with grandparents. Others may consider Japanese high school or university entrance exams. When goals differ, so does whether school Japanese instruction alone suffices or whether additional home study is needed. We have organized guidelines into five tiers:

If your goal is tier ② or higher, start by having your child read and write grade-level texts. The sooner you identify gaps, the smaller the effort required to catch up.

5. Schools with Strong Japanese Language and National Language Instruction

Throughout Japan, there are more than 30 international schools—confirmed through official sources—that offer classes for native Japanese speakers or teach "Japanese Language Arts" using official Japanese curricula. When including integrated schools (ittō-kō) where students learn most subjects in English but study national language instruction in Japanese, the options expand further. However, it is important to verify that "having an advanced Japanese course" and "learning the same content as Japanese national language instruction" are not the same thing.

For families wanting to develop Japanese language skills within the school setting, we have compiled a reference list of schools where specific Japanese language instruction details are confirmed through official school information (as of September 2026). We have not included schools that merely state they "offer Japanese instruction." The schools are listed in no particular order or ranking. Since some schools do not publicly disclose hours or other details, please contact individual schools for further information.

Before Reading the School List: Three Types of Japanese Language Instruction

Even though all are called "Japanese language instruction," schools aim for different outcomes.

① Japanese National Language Arts Type: Based on official Japanese textbooks and national curriculum standards, focusing on kanji, reading comprehension, and essay writing.

② Native Japanese Language Development Type: Classes for native Japanese speakers, covering reading comprehension, essay writing, and literature. Conducted within an international curriculum, so content differs from Japanese national language arts.

③ Advanced Japanese Through High School Type: Students can continue advanced Japanese at the high school level, such as IB Japanese A or AP Japanese.

One important caveat: "Having Japanese A does not equal Japanese national language arts." For example, K. International School Tokyo offers native-level classes and IB Japanese A, but the school itself explains that they do not cover as much kanji or classical literature as Japanese schools. If you are considering transition to a Japanese middle or high school, you must confirm these differences.

A. International Schools

Schools with instruction similar to Japanese National Language Arts (Type ①)

Schools in Tokyo Metro and Kanto Region (Primarily Types ② and ③)

IB Japanese (Native Speaker Level)

Schools in the Kansai and Chubu Regions

Schools in Hokkaido, Tohoku, Chugoku, Kyushu, and Okinawa

For detailed information about Japanese language education at NLCS Kobe, see our NLCS Kobe overview article. For Harrow Appi and Rugby School Japan, please refer to our comparison article on Japan's three leading British boarding schools. You may also find our IB curriculum guide helpful for understanding IB Japanese A.

B. Schools Where Japanese Language Arts Can Be Studied in Japanese: English Immersion and IB at Government-Approved Institutions

For families who want their children to learn in English but also want Japanese language arts (kokugo) taught with the same rigor as in traditional Japanese schools, schools that follow the Ministry of Education's curriculum and incorporate extensive English instruction offer another option. These "government-approved" schools (ichijōkō) provide Japanese language arts classes and qualify students for Japanese middle school, high school, and university diplomas.

In the Tokyo metropolitan area, schools such as Hiroo Gakuen and Mita International Academy establish international programs within government-approved schools. Our guide to international courses at government-approved schools explains the differences and compares major schools in this category.

Four Questions to Ask When Comparing Schools

This list is just a starting point. When you visit schools or attend information sessions, be sure to ask these four questions:

1. How many hours per week is Japanese taught?
2. Are there classes specifically for native speakers?
3. How far do they go with kanji, essay writing, and classical literature?
4. Are there times when other subjects are taught in Japanese?

It's also reassuring to ask which class your child might enter now and which course they could progress to as they advance grades.

6. Home Study of Japanese Language and Associated Costs

At home, the main options for Japanese language study are correspondence education (from around ¥3,000 per month), Kumon Japanese language instruction (approximately ¥8,000 per month), and online Japanese tutoring or private tutors (from ¥25,000 per month). You may see references to "supplementary Japanese schools" (hoshūshū jugyōkō), but these are schools for children of Japanese nationals living abroad, so families living within Japan are generally not eligible.

You may occasionally read that "international school students attend supplementary school on weekends," but supplementary Japanese schools are designed for children of Japanese families living overseas to study in Japanese. For families with children attending international schools in Japan, a practical approach combines the following methods (costs shown are examples from 2026; please check each provider's website for the latest rates):

Reading Shouldn't End With Simply Reading

Reading Japanese books is certainly important, but "reading X minutes daily is enough" is not the right approach.

We recommend creating a cycle like this: Read in Japanese → Discuss the content in Japanese → Use newly learned vocabulary → Occasionally write down your thoughts. This naturally increases exposure to language skills that conversation alone cannot easily develop.

7. If Your Child May Pursue High School or University in Japan

Surprisingly, children who attended international schools in Japan are not eligible for many Japanese universities' "returnee" (kikokushijo) entrance exams. Most returnee entrance exams require the applicant to have attended school overseas, which excludes students from international schools in Japan. If there is any possibility of your child attending a Japanese school later, it's important to confirm early which entrance exam pathways will be available alongside Japanese language preparation.

For example, Waseda University's Faculty of Education returnee entrance exam (2027) requires attendance at an overseas school for at least two years and explicitly states that graduates of foreign schools in Japan are not eligible to apply. Additionally, certain programs require a written Japanese language examination.

It is not guaranteed that "because my child attended an international school, they can use the returnee exam" or "strong English skills mean Japanese isn't necessary."

The same applies to high school. Returnee entrance exams typically have conditions about overseas residence, and even entrance exams that consider international school experience may require a Japanese language test. Since eligibility varies by school, it is essential to review entrance requirements well in advance.

Here is a timeline for preparation by grade level:

While in primary school: Continue studying grade-appropriate kanji and reading comprehension without stopping entirely.

Upon entering middle school: If considering a Japanese high school, attempt an actual Japanese language entrance exam to gauge the level of difficulty and identify gaps.

Upon entering high school: If taking a Japanese-language entrance exam, prepare for reading comprehension, summarization, essay writing (bun-ron), and interviews.

Summary: For Japanese Language Development, Planning Matters More Than Effort

When it comes to Japanese language for international school students, the focus should be on kanji, reading comprehension, and essay writing rather than conversation alone. The gap often becomes visible around the middle grades of primary school. Developing Japanese language skills does not hinder English development; rather, it becomes the foundation for learning. And how much to pursue depends on your family's goals.

This is why we recommend that families first discuss together: "At age 18, what would we like our child to be able to do in Japanese?" ELT's free counseling sessions allow us to listen to details about your child's school Japanese instruction and current reading and writing ability, then work with you to clarify what needs to be done and how far to take it. If you feel that your child's kanji or essay writing may be falling behind peers the same age, please feel free to reach out.

About the Sources for This Article

This article was created based on research in bilingual education (Cummins, 1979, and others), essay writing research at an international school in Tokyo, a government-funded research project on Japanese essay writing among bilingual children, official information from various international schools, Ministry of Education materials, and 2027 entrance requirements from universities and high schools (verified September 2026). Primary sources are listed in the references at the end of the article.