Space Family Carlvinson v08 c095Octonionic
The family does something completely normal, but things get complicated, as is usual.
On page 142 (file 144), Densuke is reading something called “Manga New Youth”. There's a Chinese magazine called 新靑年, “New Youth”, but the reference appears to be to the Japanese “New Youth” (especially with the cover being an abstract style-ish portrait) which used the same characters. I don't believe it was ever a manga magazine, so that's probably part of the joke. From what I can tell, that magazine went defunct in 1950, so the stash Densuke found was old indeed.