Even after Riya regains consciousness, Atsushi feels that he should continue to look after Riya, and he gives Riya a key to his apartment. Little does Atsushi know that he gave the key to Riya's other half.
Even after Riya comes to, Atsushi feels he should keep an eye on her and gives Riya a key to his place. Unbeknownst to Atsushi, he gave the key to Riya's other half.