Please support the author (18master) by buying originals on dlsite or supporting them on Pixiv Fanbox. Supporting authors is the only way we can incentivize more hentai like this to be created.

Just as a heads-up, the notation you're using on minutes ("), which while technically accurate is not something that most English readers would be able to parse, much less consider natural. That notation for minutes is only used for its navigational sense, not in the sense of time passage, and most people would read it as being a notation for inches, which would make no sense in context. If you want to abbreviate minutes, using "min" (e.g. 2min, 5min, etc) is the standard practice.

Base +7

the notation (") can also mean inches with (') being the notation for feet. yet another reason to maybe not use these notations. first time i read this was as inches rather than minutes which left me confused at first

Base +8