This Delinquent-Kun Is Ungrateful summary:

Suddenly living together with the most easily flustered man!? A gap love, a difference in age and generation!Gaku, the somewhat nostalgic young delinquent, showed up in front of Akira, a high school teacher around thirty years old. Moreover, why are they suddenly living together!? This is the heart-throbbing, awkward love between Gaku, a cute, earnest, slightly foolish boy who likes to look good, and Akira, an older woman who unconsciously leads him around the nose!