I already knew this Japanese font. However, I also want this to be downloadable too in this website. Please grant this request for us.

Nope;
G2サンセリフ B (G2 Sans Serif B) is a commercial typeface designed by TypeBank, a Japanese foundry that is now part of Morisawa Inc.
G2サンセリフ B can be found on their website https://www.morisawa.co.jp/fonts/specimen/1646
G2サンセリフ B is included in several Morisawa font products and services, such as:
- Morisawa Fonts (Standard, Educational Institution, Public Organization)
- Morisawa Fonts Select8 and Select24
- Morisawa Fonts Webフォント
- MORISAWA PASSPORT (including Academic Edition)
- MORISAWA PASSPORT for iPad (Standard Pack)
- TypeBank PASSPORT and Select Pack 1 / 5
- Embedded fonts and server application font licenses
- TypeSquare