Sorry for the delays. I had to take some time off, and then we were catching up on another series, but we're more or less back to our "regular" release schedule now.
marinating in 5-10% acid is fine for a day, though overnight is fully sufficient. marinate in enzymes like kiwi or pineapple for 24h and you will have a fucking goop that a laboratory might identify as meat after extensive testing.
Bread isn't a traditional part of Japanese cuisine, so I suppose it makes sense they simply didn't think of not using jam at all under those circumstances. Unless that toast looking bread itself is already sweet, like the American type bread.
I swear, the woman in these type of mangas are children. Always causing problems. The dudes always seem to be level headed and fix their fucking problems.