The Girl I Saved on the Train Turned Out to Be My Childhood Friend, Vol. 1 (manga)

Ryou Takamori intervenes when he sees a groper on the train, only to discover he has saved his estranged childhood friend, Hina Fushimi. They lost touch in middle school as their social lives diverged, with Hina becoming popular and Ryou remaining a loner. This unexpected encounter could be the chance Hina has been waiting for to reconnect with Ryou. She hopes it will lead to rekindling their friendship and possibly more, if Ryou can recognise the signs.