AI Essay Support System "Sakubun Jaws" for Foreign Learners of Japanese Released Today

Remedies Inc. (Headquarters: Chiyoda-ku, Tokyo; Representative Director: Tsuyoshi Fukuzawa), which operates the AI proofreading tool "wordrabbit," announces that it has been responsible for developing the core AI engine as a technical collaborator in a joint research project with the National University Corporation University of Tsukuba and the National Institute for Japanese Language and Linguistics. Today, we are pleased to announce that "Sakubun Jaws," an essay correction and evaluation system for Japanese language learners, has been publicly released for free by the University of Tsukuba as a result of this project. This system utilizes our proprietary AI technology to automatically evaluate and correct essays written by non-native Japanese speakers, thereby reducing the burden on teachers for corrections and supporting autonomous learning tailored to each learner's level.

Challenges for Japanese Language Learners: Enormous Essay Guidance Costs and the "Over-Correction" Barrier of General-Purpose AI

In the field of Japanese language education, "essay guidance" is an indispensable process for improving learners' abilities. However, it is also a highly individualized task that places a very heavy burden on teachers. While the advent of generative AI has raised expectations for automatic correction, conventional generative AI has faced challenges such as "over-correction," where it ignores the learner's intent and corrects too much to sound like a native speaker, and "presenting difficult expressions that do not match proficiency levels," leading to mismatches.

To address these challenges, this project integrates specialized AI proofreading technology with academic perspectives. By grasping the learner's level and providing optimal advice while respecting the original expression, the project aims to reduce the burden on the educational現場 and achieve high-quality autonomous learning.

Functions of "Sakubun Jaws"

1. Automatic Essay Correction

An AI essay correction system specialized for Japanese language learners corrects essays. Instead of immediately displaying the correct answer, it highlights areas that need review with underlines and hints.

2. Automatic Essay Evaluation

Evaluation results are displayed for each element such as grammar and vocabulary. Detailed evaluations allow learners to grasp their strengths and weaknesses in detail and apply them to their learning.

Comment from Professor Takuya Iwasaki, Faculty of Humanities and Social Sciences, University of Tsukuba

In recent Japanese language education, with the diversification of learners, there is a growing need for evaluation methods that can quickly grasp language proficiency characteristics and link them to appropriate class placement and instructional planning. Existing Japanese language proficiency tests did not include online writing placement tests. Therefore, "Sakubun Jaws" was developed, equipped with a mechanism to quantitatively and visually evaluate learners' proficiency characteristics from the perspectives of "vocabulary" and "grammar." Compared to conventional monolithic level judgments, it is expected to provide more diagnostic information, which can be utilized not only for class formation but also for individualized instruction and curriculum design.

Comment from Professor Kei Ishiguro, National Institute for Japanese Language and Linguistics

This system was developed through industry-academia collaboration based on data from the "W-CoLeJa" longitudinal essay corpus constructed at the National Institute for Japanese Language and Linguistics. In its development, we emphasized the concept of "feedback that doesn't over-correct," which was conceived to respect the learner's original essay expression while providing feedback appropriate to their level. We expect this to significantly reduce the correction burden on Japanese language teachers in the field and create an environment where learners can autonomously engage in essay learning.

Features of "Sakubun Jaws": Unique Design that Respects Learner's Intent

1. No Excessive Rewriting

To respect the learner's intent, it clearly distinguishes between "obvious errors" and "suggestions for more natural expressions." It suppresses excessive rewriting, which is a common problem with generative AI corrections, and proposes corrections that leverage the learner's own writing.

2. Suggestions Tailored to Learner's Level

The feedback level is automatically adjusted according to Japanese language proficiency. For beginners, it focuses on basic grammar, while for intermediate and advanced learners, it suggests more natural expressions, enabling gradual learning tailored to proficiency levels.

Usage Scenarios for "Sakubun Jaws"

1. Teacher's Essay Guidance

AI points out formal errors such as basic grammar and notation, allowing teachers to concentrate on guiding content, structure, and logical development.

2. Learner's Self-Study

It supports self-study for various purposes, such as level checks for job hunting or further education, and preparation for descriptive questions in qualification exams.

"Sakubun Jaws" Website URL

https://s-jaws.cegloc.tsukuba.ac.jp/

About "wordrabbit"

"wordrabbit" is an AI solution specialized in correcting Japanese texts. In proofreading tasks traditionally performed entirely manually, wordrabbit enhances professional quality control as a specialized AI that deeply interprets the nuances of Japanese and rules of specialized fields.

About Remedies Inc.

Remedies is an AI startup company that develops Japanese-specific solutions based on its unique technology related to Japanese x AI. In 2024, it was selected as a finalist in "IVS LaunchPad," one of Japan's largest startup pitch contests, and in 2025, it was selected for the Tokyo Metropolitan Government's Women's Venture Growth Promotion Project "APT Women." The CEO and CTO participate as joint researchers at the National Institute for Japanese Language and Linguistics. Remedies holds patents in the Japanese language domain and, for "Sakubun Jaws," provides an AI model that responds to unique error patterns of Japanese language learners and correction logic based on advanced dependency parsing. Through the development and design of the core AI engine, Remedies supports the individualized optimization of Japanese language education and the advancement of evaluation processes.