During summer vacation, I'm staying at my brother's house, helping out with the kid since he and his wife are both busy working. My brother's wife, Fumika-san, just returned to work after maternity leave, but since they're still anxious about leaving the baby with strangers, I ended up taking care of the little one. Fumika-san is incredibly beautiful and kind; honestly, I'm jealous of my brother. She's just a bit airheaded, or rather, she has a clumsy side to her. Even right now, she's like that. Despite me, her brother-in-law, being in the same room, she's lifting her clothes and breastfeeding without a care in the world. "My breasts have been so full lately... they're practically bursting~" She doesn't seem to notice my gaze stealing glances at her breasts at all. My arousal reached its limit, and before I knew it, the words slipped out: "P-please let me drink your breast milk too!" Of course, it didn't end with just breastfeeding... From that moment on, my days of gulping down my sister-in-law Fumika-san's breast milk while fucking her like crazy began.