My First Love's Kiss Novel Volume 1 was written by Hitoma Iruma.

Takasora Hoshi’s life is upended when a girl from her class named Umi Mizuike and her mother temporarily move into her family’s cramped apartment. From the outset of this arrangement, Takasora finds herself annoyed by Umi’s behavior…and her good looks. And though the two girls initially agree to avoid interfering in each other’s lives, Takasora can’t help but start to wonder where Umi keeps wandering off to at night… From the author of Adachi and Shimamura comes the bittersweet tale of two high school girls whose lives are thrust together under the same roof.