it is exactly as it sounds. It's Giyuu's demon boyfriend, Tanjirou.

Yuno has time off so does asta they decided to go back to their town. They got their own room seprate from the children because they were older, Yuno notices that asta only changes in the bathroom what happens when he asks why? Yes there is smut Warning (self harm) (depressing/suicidal thoughts) dont read if these things trigger you