福田の大学別シリーズ一橋大学入試問題解説2020年度版

It is an app for examinees who posted all the entrance examination questions of Hitotsubashi University for the past 4 years and can see detailed answers and polite commentary videos. See the problem. Solve it yourself. Check and confirm the answer. If you don't understand it, understand it by watching the commentary video. This cycle can be realized with this application alone.