Adult PC Game: Let's Make It With Tentacles! Dirty Boy Daughter, Arrogant Yankee vs. Tentacle Mansion v1.0 by Kinokko Archive

Overview:
Kotaro, a famous local delinquent, is asked by his younger brother Yasutaka to confront a mysterious old man.
However, due to Yasutaka's betrayal, he is captured in a tentacle mansion.
Will Kotaro be able to escape from the mansion full of monsters without becoming a bitch!?​