"Even though I don't want to... Why am I getting so wet?" The man's persistent and repeated caresses are making me overflow, even though I don't want to feel it...no! --Kana and her boyfriend's brother and his wife are on a trip to a hot spring before she marries him. While she is sleeping, she feels more than usual when she is carressed by a tongue... but it is her boyfriend's brother!? "You're getting loud. Is it okay if he finds out?" I don't want to do this with anyone but my boyfriend... As her boyfriend sleeps, another man's cock is thrusting into Kana's secret place...!

(Source: Fanza Comics, translated)

Notes:
- Includes one extra chapter.
- Originally serialized as a web manga under the title Konzen Nettorare Haishin: Kareshi no Ani ni Irerareteru... (婚前寝取られ配信〜彼氏の兄に挿れられてる…).
- Subsequently published on mobile reading platforms with each chapter split into 3 ‘episodes’, resulting in 30 episodes.