My first thought was "this is some sick joke." A little research revealed that the character in question is Afro Tanaka, a manga character invented in 2002 by Masaharu Noritsuke. Afro Tanaka is a disaffected high school student who gets involved relatively boring and mildly funny situations. His afro remains unexplained. It's what makes him different than his peers. Whether this is slightly racist type of negritude or merely observation on the part of Noritsuke also remains unexplained. The manga, like the hairstyle makes its occasional comebacks.
This design and promotion are somehow linked to Mini Mart's 30th anniversary. Is Mini Mart actively working to break down stereotypes and promote acceptance? Japan is notoriously racist even as it consumes and reinvents everything it can from other cultures. One is unsure of Afro Tanaka's racial heritage. Is he mixed blooded? Is he just playing at blackness? Is it natural? And does it matter?
No matter, the cleverness of the packaging is arresting, The product itself less so.
Melon pan, or what one may call melon bread, is a ubiquitous staple of Japanese bakeries. Though it is often melon flavored, the name actually comes from the sugary crunchy cookie-like dough that thinly covers the lump of sweet cake that makes up the melon pan. The surface gets a leathery melon rind look. Black melon pan is merely a pastry of the same sort with a black sugar coating. In the Afro Tanaka version, the black "melon rind" covers a sweet/bland chocolate cake which encloses a standard chocolate custard. All in all, it's sweet, a little chocolatey, and not much else.