Only in My Dreams, by Incandescentflower – 30歳まで童貞だと魔法使いになれるらしい | 30-sai Made Doutei da to Mahou Tsukai ni Nareru Rashii (TV) [Archive of Our Own] | https://archiveofourown.org/

When they entered the hotel room, Adachi went from internal panic to full on meltdown.

The room only had one bed.

Source: Only in My Dreams, by Incandescentflower – 30歳まで童貞だと魔法使いになれるらしい | 30-sai Made Doutei da to Mahou Tsukai ni Nareru Rashii (TV) [Archive of Our Own] | https://archiveofourown.org/

A sweet and perfect first time fic using one of the best tropes.