Talk:Sei/@comment-27409381-20180325234246/@comment-27409381-20180402033713

It's just as you said, there are only hints, nothing confirmed. It's just implied they spent a night together. Rou spent many nights with some elf girls, yet those elves and Rou aren't a couple. It's probably the same with Sei and Sato, plus they were drunk, plus it's said by the author that Sato is searching for a boyfriend, and since Sei doesn't have a boyfriend too, then they were probably just lonely, and slept together because of a moment of weakness.