ハイキュー!! - ひかりの子 (Doujinshi)

Pairing: Iwaizumi x Oikawa *Hikari no Ko 1* was published in [SIDE.1 airport](https://www.mangaupdates.com/series.html?id=156936) while *Hikari no Ko 2-4* were released as their own books. The whole series is the sequel to [Tanoshii Jigoku wo Irodoru nara](https://www.mangaupdates.com/series.html?id=147387)