My First Love's Kiss Novel Volume 2 was written by Hitoma Iruma.

Ever since Umi Mizuike suddenly became her roommate, Takasora Hoshi can't get her out of her head. Umi is quiet, beautiful, and probably Takasora's first love. Unfortunately, Umi is already in a relationship of sorts, with an adult woman who pays her—and before Takasora can even process this, the woman invites her out to a hotel for a “girls' night,” too. Could this get any worse?