The protagonist enters (or finds out about (I use the word "discover" if such a thing happens)) a "world" (using this term loosely) / time period unlike their own. Does not include entering a game (game aspects are accepted however).
these are manga that need an anime or second anime be cause the first one sucked, or was incomplete. Alphabetical order, i add a description if i feel it's necessary.
This list is in no particular order whatsoever , but consists of my most favorite manga titles.