After six years of dating, Takuya gets dumped by his childhood-best-friend-turned-girlfriend. Takuya has sunk to his lowest—and then a message comes in from Naoki, his ex-girlfriend's little brother. Naoki, who has grown into a stunning, long-haired young man, shocks Takuya with words that just might turn his world upside-down... (Source: Houbunsha)

Motokano no Otouto ga Kawaii tte Hanashi, originally released under the title Motokano no Otouto (元カノの弟), is a web manga published on the author's Twitter and pixiv accounts since December 27, 2018. Official serialization started in Comic Trail on December 6, 2019. The series is published digitally in English as My Ex-Girlfriend's Little Brother Is So Cute by Houbunsha through MangaPlaza.