See You Tomorrow, Everyone

After Watarai Satoru graduated from elementary school, he dropped out of school and decided to live within his apartment complex, never to venture outside. Satoru then meets his old friends as they are coming back from their middle school classes. Satoru has now gotten a job at a cake shop within the apartment complex and eventually gets engaged to one of his friends. Satoru, still lives within the apartment complex only, but, as time passes, more of his friends leave...
(Source: AsianWiki)
~~ Adapted from the novel "Minasan, Sayonara" (みなさん、さようなら) by Kubodera Takehiko (久保寺健彦).