Touko-san wa ii Otona ja Irarenai

The hard-working designer Touko (27) is an expressionless person by nature. One day, she was removed from a work project because of it, as it made her seem hard to work with. On the advice of a junior colleague, she tried using a dating app to train herself on how to interact with other people, but her best match turned out to be an 18-year-old high school student...? (Source: Ganma!, translated)