The twin haired girl was a lolicon/otaku with a hyperactive personality, and he likes very girly things. His tendency of putting himself at the center of embarrassing situations and letting his male imagination run wild, only to then run away like a scared kitten especially makes it funny and endearing. I would like to see a whole series just on his antics.
Continuation of the series involving three cousins of a family carrying a gene causing them to turn into girls if they are virgins at a certain age. Here, the loli one wants to go shopping for a bathing suit because she has a fantasy of going to the beach with a bunch of girls, even though she's still an otaku loner just like she was as a boy. The still-very-boyish cousin goes along with her to the store. Both are horrified when the shopkeeper suggests a tiny bikini. Boyish one picks a competition-type one-piece, loli picks a frilly bikini. Loli one, who had previously said things like "small tits are the best" has totally changed and is now jealous of boyish one's huge boobs. They finally make it to the beach and meet their other cousin from Chapter 1, who they find wearing the slutty bikini from the shop. Cousin says, "My sister picked it out for me. She said girls all wear ones like this." The other two shake their heads. 2nd-to-last panel: Sister: "Pfft. I can't believe that idiot actually wore it." last-panel: Cousin: "Oneesan!" Boyish-one: "Let's go get yakisoba." Loli-one: "Good idea."
@sensualaoi She was was definitely always a girl. She clearly has zero regret about living as a girl now. Both the other cousins dreaded this happening, while she intentionally made sure it'd play out the way it did. She's even upset that she didn't end up with bigger boobs than what she got, while her "boyish" cousin clearly isn't thrilled that he can't live as a guy anymore.