His father remarried and he has two adorable younger brothers who are always rivals for his older sister! While Ken-chan is out, Dai-kun, who wants to have his older sister all to himself, is making out in the kitchen. Just as he's about to insert his penis into his older sister's anus, Ken-chan returns home, celebrating his birthday... That's right, his older sister is a beautiful transsexual with a penis! Ken-chan had promised to have sex with his older sister...
