Mahoutsukai no Yakusoku

[MangaDex]

 

[CardinalBirb]

where can I read this? can't seem to find any site to read this on? is it originally something else?

 

[eru_P]

where can I read this? can't seem to find any site to read this on? is it originally something else?

This is based on the mobile game of the same name Mahotsukai no yakusoku or Promise of Wizard, someone was translating it on tumblr, but I think they didn't finish it.
It is difficult to find since the volumes are only obtainable physically and afaik there aren't raws or scans available online, so far there are only two volumes (volume 3 is going to be released later this month if I recall correctly), still if you're interested in the story you can read the story of the game (by healingbonds on twitter), it's basically the same (and even more detailed since the manga omitted small details here and there).

Good luck!