A full version app for Android, by 株式会社EIHSOFT.
This app provides free access to the first-grade math curriculum from the Ministry of Education, Culture, Sports, Science and Technology. You can practice it offline, which is especially convenient for those who have limited time or live in remote areas.
This app includes all the content for the first-grade math curriculum, which is divided into two parts:
1. A set of problems that can be solved with no effort (easy)
2. A set of problems that require some effort (medium)
3. A set of problems that are difficult (hard)
Each problem has several difficulty levels so that you can step up according to your child's progress.
This app also provides the commentary on the answers so that you can check your answers and see why you got the answer you did.