Sorry... my suggestions might not be that great...

Eensy-Weensy Monster -- kinda...
Vampire Knight -- eventually...
Black Bird -- based on what's scanlated so far, it's not that smutty (yet?)

Quote from ShadowSakura

Quote from juls91

nabari nou

could it be you mean nabari no ou?

i fixed it after i posted .. gosh i didnt even blink 🤣

** "It's so warm that, Before the snow has a chance to stick, He melts it for me." **

And Les Bijoux! Just recommended it on another thread, and then realized that it actually counts for this request, too... Keep in mind that it's a gender-bender - but I still think of it as 'straight', because the gender-bending character is a woman by the time the 'enemy male' makes a move on her. And even though he's the enemy, he's also actually the male protagonist and her only viable romantic interest... Pretty rare, huh? 😀

In Zombie-Loan Shiba is obsessed with Chika. Both are guys but it's not shounen-ai. In Tsubasa Reservoir Chronicles there are the vampire twins and the two brothers but that's just in the later volumes.. And X of course with Kamui and Fuuma! Then there is Tokyo Babylon with seishiro and subaru, it's shounen-ai but worth reading! Most of CLAMP's work are like this i think. 😃