Oshi ga Buka ni Narimashita

Sayaka Tsuneda, age 29, works at an advertising agency when one day a suit-wearing angel descends before her very own eyes?! The idol that gave her life worth meaning is now her co-worker and she's in charge of his training... Is this a dream?! Sayaka struggles to handle her own feelings as the two of them grow closer and closer. How will this awkward fan girl's love story end?!

(Source: MangaPlaza)