Houteki ni Mondai Nai Ane to no Kankei

An older sister and her younger brother genuinely loved each other.

That day too, these two siblings were secretly having sex in their parents' house, muffling their voices while doing the deed. But after deciding to pull out and finish in the usual manner, the younger brother is surprised by his older sister declaring that she has decided to move out of the family house, and enroll in a university located in another prefecture.

It's been one year since then. Hoping to see her again, the younger brother searched for the apartment his sister lives in. She was on her way back when she happened to see her brother looking around, and without caring about onlookers, she came running to his side and gave him a french kiss in public. The two were delightfully reunited in her room. When he asked her about her life in the Law Department of her university, she told him she was studying laws related to marriage. She learned that there's no clear basis for the prohibition of blood-related marriages and incest, so as an older sister and younger brother, she emphasized that they should be able to love each other without any problems whatsoever.

Seeing her like that, he subconsciously thought "I love my sister." and the words slipped from his mouth. Hearing that, she suddenly took out his dick and gave him a blowjob. It's been a long time since she last blew him, so he came immediately. But this time, they're not at their parent's house. Set free, this older sister - younger brother pair will now have unrestrained sex. Today is the first creampie!

(Source: DMM, translated)

Note: Published in Comic Grape Vol.100