Maybe I'm Your Steppin' Stone (Yaoi Manga)

Kousei seems pretty popular with everyone-the other construction workers, the clerk at the convenience store-just about everyone except his ex-wife. Kenji Hirose, the clerk at the convenience store, has become a doting uncle ever since he realized that his niece and Kousei's son attend the same nursery school. When the school's sports tournament leaves Kenji injured, Kenji's more than willing to take advantage of Kousei's nursing ability and wait for the opportunity to pounce!