Osamu Tezuka's Last Mystery of the 20th Century

Synopsis

New Year's Eve 2000. An eternally juvenile Tezuka Osamu meets his creations for a New Year's Eve party at the Dr. Tenma's mansion, but before the event begins he suddenly disappears from his room in what looks like a kidnapping. A classic mystery setting for, at the end, a lovely homage to the man behind the genius. (Source: AniDB)