Boku no Nee-san

Boku no Nee-san manga summary: A spin-off of Little President, featuring former delinquent Aihara Masane, her step-brother Jun, and her step-mother Chitose. Most of the humour comes from how Masane and Jun are madly in love with each other but can't figure out how to express it, and how Chitose is probably more OK with this than she should be.