Loner Life in Another World Vol. 6 (manga)

"OPEN SEVEN DAYS A WEEK! Having begun his plan to turn Omui into an independent trade hub, Haruka sets about improving the local shopping facilities in record time. But his behavior doesn't go unnoticed, and the lord of an exploitative neighboring territory doesn't take kindly to the idea of Omui going independent. Cue the deployment of an invisible menace... One who relentlessly takes notes! Haruka can't exactly enjoy his loner life with a stalker shadowing him at every turn, but what's a man to do? Our hapless hero decides to just go about his business diving for more dungeon treasures. Surely the situation will just solve itself, right? Right?"