It's true that their characters are a bit different compared to what they were in Hitorijime Boyfriend, but it's mainly due to the fact that Arii-sensei didn't plan it to be a long series, it was a one-shot right from the beginning. But she eventually decided to continue the story with a spinoff that's Hitorijime My Hero. While My Hero's main focus are Masahiro and Kousuke, I can assure that Hasekura and Kensuke are pretty much the same they were in Boyfriend (won't be spoiling or anything, but things happen in latest chapters). If you've read My Hero closely (at least up to the translated chapters), there are a few times mentioned how Hasekura isn't that clingy with Kensuke because he isn't into PDA, but he makes it sure that no one can easily touch Kensuke. He wants to show his affection in private. And their private time seems to be pretty limited and for some reason Arii-sensei doesn't want to go to details regarding that not that much, as My Hero's focus is on Masahiro and Kousuke.
And what comes to Masahiro's character. Well, he was different character in the beginning of Hitorijime Boyfriend, but in the last chapters he started to feel more like what he's now if you examine him more (=・ω・=)
Am I the only one who finds their characters are way off of their personalities in the prequel and this? I mean I thought Setagawa was supposed to be a cool and idgaf kinda guy but here he's rather super timid and obedient? And since when did he suddenly start cooking and bringing homemade meals to school I thought he ate school bread? Also in the prequel it was the seme (Hasekura) that kept clinging to the uke and persuading on physical activities but in this book it's the other way around like whet?????
How can they act so different lol