Gokutsuma Days: Gokudou Sankyoudai ni Semaretemasu

Gokutsuma Days: Gokudou Sankyoudai ni Semaretemasu manga summary: One day Sakura, a socially withdrawn otaku, saves the life of the Amogumi’s leader. How in the world did she become the highest ranking wife?! <br>The leader declares to the three grandsons that, “The person who defeats Sakura-san will become the next leader”. <br>The eldest son is weak but kind, the second son seems fierce and aggressive, and the third son is a level-headed intellectual. The three of them are all highly skilled and stubborn in their own ways… <br>How is this shut-in the ultimate wife?! Jeez, no thank you. “Yakuza Harem”, start!