UnluckyStrike's Manga

The age gap is apparently 6-7 years, mc is 16 and her supposed romantic interest is likely 22-23. Mc seems to like her from the first sight.
Personally, I do not think such an age gap is that frightening, many married couples have age difference like that. Of course, mc is a bit too young, but, if there is no pressure, manipulation or other malicious intents involved, I don't find it that catastrophic. After all, in many developed countries 16 is the age when person is deemed capable to have their own romantic experience. If the young person is reasonable and can think for themselves It seems okay.

I feel like that Magic Shinkoku Sake will be made by bartender girl, and the ogre girl will drink it by kissing the bartender.

Actually, it is quite dramatic, being presented with a choice whether to make other person suffer or suffer yourself and let those close to you get hurt.

Technomagipunk or whatever you call this. Art is nice, the setting and story seem pretty original.
Demon King, defeated by the hero, resurrected only to find the known fantasy-magic civilization gone, with new technomagical world of fused Earth and Alnez.