Every Shin Mizukami one-shot has a theme, & this time it's "adopted sons stealing from fathers."
Also...the cover...there's no story in this book that it belongs to. I'm sure it comes from a short story in another one-shot; I'll write it down when I find it.
Dreamy Pavilion: Fei-Yen (or Hien) is a crossplaying Gēwǔ jì/Xìqǔ/Kabuki actor who is sold out to a old politician. He is confiscated by the man's bratty son, Do-Sho Sei-Jo, whom intends to "share" him with all of his friends, & then becomes indignant when he finds out Fei-Yen is not a woman. His friends knew from the start & think it's funny. Despite nearly being raped, Fei-Yen decides hetero Sei-Jo is a safe alternative to his father & befriends him. Sei-Jo learns that rape is wrong & that maybe he's not as straight as he thought, & when Dosho Sr. decides he wants to pimp Fei-Yen out to his political buddies, Sei-Jo has some life changing decisions to make.
Harem for Two: A Comedy about a lusty young king, his bloodthirsty bodyguard/Waifu, & one very confused horse. Marvel at the world's most hilarious fountain.
Resigned Decision: Set in modern-day Japan, rather than ancient China, like the rest of the stories. It's an "Odd Couple" story about two very different men who don't get along but live together anyway. Dan; a violent slovenly no-class freeloading teen, & Kanda; a swank neat-freak detective wh easily caves in to peer pressure. As their relationship improves slowly overtime, Dan is unwittingly sabotaging all of his own life goals & Kanda ends up sexually confused.
Pavilion of Destruction: This story is a twist on one of her older stories; Rikara, only that the lovebirds have been merged into a single protagonist. Spoiled brat Sai-Mon Kei (hehe, sounds like Sea Monkey) has had little to no interaction with his bisexual womanizing harem-owning step father. The one time Sai-Mon Ei notices him, he hits on him. At first Kei is pissed, then he realizes he's super turned-on & totally loses his shit.
He becomes rebellious, breaking expensive things, scalps his father's harem, & rapes the first boy he comes in contact with, then goes out of his way to piss off Ei at every turn.
It should be noted that there's a surprising amount of hentai in this story, despite it being yaoi. It's also probably the only Mizukami manga with hentai in it.
! Ei has a strong preference for women, Kei is strictly gay, but gets a woman pregnant so his father can't marry her. Kei marries the woman his father wants out of spite while continuing to collect male prostitutes.