The Angel Next Door Spoils Me Rotten: After the Rain

Otonari no Tenshi-sama ni Itsunomanika Dame Ningen ni Sareteita Ken: after the rain
お隣の天使様にいつの間にか駄目人間にされていた件 after the rain

Source

The Angel Next Door Spoils Me Rotten
Otonari no Tenshi-sama ni Itsunomanika Dame Ningen ni Sareteita Ken· お隣の天使様にいつの間にか駄目人間にされていた件
novel

Amane lives alone in an apartment, and the most beautiful girl in school, Mahiru, lives just next door. They've almost never spoken—until the day he sees her in distress on a rainy day and lends her his umbrella. To return the favor, she offers him help around the house, and a relationship slowly begins to blossom as the distance between them closes... (Source: Yen Press)

Parent Story

The Angel Next Door Spoils Me Rotten
Otonari no Tenshi-sama ni Itsunomanika Dame Ningen ni Sareteita Ken· お隣の天使様にいつの間にか駄目人間にされていた件
manga

Amane Fujimiya lives alone in a messy apartment—right next door to Mahiru Shiina, a veritable "angel" who's the smartest, prettiest girl at school. When a chance encounter on a rainy day draws them together, Mahiru finds herself spending more and more time helping Amane get his life in order. And though they both insist they have no intention of dating the other, slowly but surely, something more than friendship begins to blossom. (Source: Square Enix)