Chicchai Kanojo Senpai to Douseishimasu.

Takase has just landed a job at a real estate company when he meets a tiny, attractive woman at work and decides to ask her out. And eventually, they find themselves moving in together together. Gradually, they build a foundation for a life together, until finally........! The final chapter of the Chicchai Senpai series.

(Source: Houbunsha, translated)