I can't think of other examples about death and mourning at the moment (possibly I will kick myself about something obvious later) but I think you would find these interesting.

Astro Boy, one of the most famous manga/anime characters in Japan, was made a Japanese citizen on his birthday on April 7, 2003. (He's a boy robot who first appeared in 1951 with a creation date of April 7, 2003.) There were also a few other birthday events.

There is a post in the Japanese government to promote animation which is held by a popular anime character.

(I then Googled a bit for actual death related things and found that there was a small funeral in France for Goku of Dragonball, and there was also a funeral for a Fists of the Northstar character in a Buddhist temple in Tokyo a couple of years ago. The article says that was the first time a Buddhist temple has been involved with a fictional funeral.)