Kanzaki Hikaru's sister-in-law has huge breasts, there's no bra that she feels fit. Kanzaki Hikaru often has a hard time shopping for bras because of his huge pair of backpacks.
When at home, Kanzaki Hikaru often lets loose her breasts because she feels comfortable. At home alone, suddenly her brother-in-law came over to play, so suddenly that she forgot to wear a bra.
Seeing Kanzaki Hikaru's sister-in-law loose her breasts made her brother-in-law shy. He did not dare to look directly at his sister-in-law, especially now that his brother was not at home.
Kanzaki Hikaru's sister-in-law is not only unafraid, even soliciting love from her brother-in-law. The two took each other into the room and made love passionately.