Shizuki's had multiple fuck buddies before! Both men and women. In an earlier volume, he says that he's actually stopped the fuck buddies thing after he started one w Yano!
Then he is bisexual, ain't no way he thinks being able to sleep with people of the same sex is being straight
Heteroromantic bisexual does exist, maybe that's what he meant by straight. Well, they ended up bending anyway, so
He is bisexual with a preference for women, the author clarified in chapter 27.1.
nahhh i thought shizuki's first time is with yano?? cause i remembered he said in ch 1, they were both straight to begin with. are you still considered straight when you're able to fuck with the same sex ??? lmao hahaha but yano's top love language is definitely words of affirmation i love him