Usagi Yojimbo has been around as long as the Teenage Mutant Ninja Turtles (created by Kevin Eastman, current owner of Heavy Metal) and the creators have collaborated on joint stories since the mid-80s. So it’s not unusual to see the definitive collections of Usagi Yojimbo being advertised here.

(Heavy Metal issue #217, January 2005 – Page 34 Usagi Yojimbo ad)