Sumi-Iri Osananajimi No Sokubaku Ga Tsurai summary:

Nanase, in her first year of working, is troubled by her childhood friend Rui; a tattoo artist who is very restraining. He’s worrisome, overprotective… and just plain restrictive! The two have been living together for five years, but they are not lovers. Nanase loves Rui, but for some reason, she can’t tell him how she really feels.One day, Nanase learns that the manager of the shop where Rui works, whom she respects, is a woman. She decides to visit her at work, out of curiosity, but…?