@lividus Since there's a disclaimer on the second page, I'm guessing this isn't meant to be taken as canon for either manga.
I know it's a disclaimer about how the work is fiction, just as the regular chapters are obviously also generally fictitious (whether or not they were inspired by real people or events in the author's life, I can't say), but the regular chapters don't have that disclaimer aside from the one in the credits page of the tankoubon volumes.