Fujisan Daifunka: Senryokugai Nitei sareta Ossan Kaishain Mochizane ga Tenpen Chii de Nariagari!?

"The world might as well just turn upside down," thinks Mochizane, a salaryman who despite his earnest dedication to his job, spends his days being belittled by juniors from other departments and struggling to keep up with an endless mountain of work. In the midst of these exhausting days, Mochizane makes a mistake at work and is forced to head to Gotenba City at the foot of Mount Fuji with his boss. Just as he reaches his breaking point and decides to quit his company, something unthinkable happens...!

(Source: Shogakukan, translated)