夏休み、俺は共働きで忙しい兄貴夫婦の家で子供の面倒を見ている。兄貴の奥さんの‘ふみかさん’が産休から仕事に復帰して、でもまだ他所に預けるのは不安だからって俺が見ることになったのだ。ふみかさんはとってもキレイな人で優しくて、正直兄貴が羨ましい。ただちょっとおっとりしているというか、抜けているところもある。今だってそうだ。義理の弟である俺が同じ部屋にいるってのに、お構いなしに服をめくって授乳を始めている。「最近すごくオッパイ溜まっちゃって～パンパンなのよね～」チラチラとおっぱいを見る俺の視線には全く気付く様子もない。ムラムラが極限にまで達した俺は気付けば口走っていた「お、俺にも母乳飲ませてください！」当然ただの授乳だけで終わるはずもなく…そこから兄嫁ふみかさんの母乳をゴクゴク飲みながらヤリまくる日々が始まった。

During summer vacation, I'm looking after the kids at my busy working brother and sister-in-law's house. My brother's wife, Fumika, has returned to work after maternity leave, but she's still hesitant to leave the kids with anyone else, so I've been asked to look after them. Fumika is a very beautiful and kind woman, and honestly, I'm jealous of my brother. However, she's a bit laid-back, or rather, a bit absent-minded. It's the same thing right now. Even though I, her brother-in-law, am in the same room, she lifts her clothes and starts breastfeeding without a care in the world. "My breasts have been really full lately, they're so swollen," she says, completely oblivious to my glances at her breasts. My lust has reached its limit, and before I knew it, I blurted out, "P-please let me drink some breast milk too!" Of course, it didn't end with just breastfeeding… and from there, days of drinking my sister-in-law Fumika's breast milk while having sex began.