Datsudoutei no Aite wa... Masaka no Aitsu!?

Fondling Kaori's full, developed breasts, I'm about to stick my dick into her pussy... But, why the hell am I about to have sex with my little sister!?
(Source: Coolmic)
Note: Originally serialized as a web manga under the title Hatsu Ecchi no Aite wa... Imouto!? (初エッチの相手は…妹！？). Each chapter is split into 3 ‘episodes’ in the English serialization.