What are two pieces of media that you can't believe share the same universe?

So, today i just learned that the Manga Kengan Ashura/omega, which is about greedy billionaire corporations having life and death fight tournaments with deep hatred rooted in bloodline feuds, ancient fighting techniques, parts of japan so ruined they have open organ harvesting and have been locked down and seen as a lost cause.

Shares the same universe as 'How Heavy are the Dumbells you lift?'
Which is a cute humor anime where a big body builder type flexis to destroy his clothing and helps a bunch of girls get in shape.

These are also not just a "same universe cause the creator said so" there are crossovers, family ties between characters from both shows and general world building that hints at it with background stuff in Dumbells that talk about the Kengan fights.

it just seems extremely wild to me that these two series exist within the same canon, and i wanted to know if there where other examples of media that has this sorta stuff in it?