Butterflies, Flowers Vol. 6 (manga)

Choko Kuze is in a relationship with Masayuki Domoto, her current boss and former servant. Now that her family’s house has been rebuilt, Masayuki asks Choko to give him back the key to his apartment, signaling the end of their living together. Not wanting to leave, she decides to give him a different key and sneaks back into his place...