Ryūzaki, the original Successor to L, investigates a case regarding a looked-room murder in Hong Kong. Later, J, an women from Wammy's House requests Ryūzaki to investigate another locked-room murder case, made by a death note. Two death note user, Yuki Shien and Sakura Aoi also appears. At the end of the episode, Ryūzaki reveals the promise once made to L with a flashback of L.