This entry includes the following chapters: 1. Oiwai Sex: Onii-chan no Tanjoubi (おいわいせっくす ～お兄ちゃんの誕生日～) released at Comiket 94, later one included in Otomari Sex Omnibus from Comiket 97. 2. Oiwai Sex 2: Imouto no Tanjoubi (おいわいせっくす２〜妹の誕生日〜) first released online in FANZA and bundled with Oazuke Sex in Comiket 95, later one included in Oyasumi Sex Omnibus from Comiket 97. The setting happens after Oazuke Sex. 3. Oiwai Sex 3: Onii-chan 20-sai no Hi (おいわいせっくす 3 ~お兄ちゃShow more