Old Man Teaching System?!

James was a very popular online male model with millions of admirers, he dies a hilarious death in the shower, the god of reincarnation thought it was hilarious and reincarnated him into an old man who is a teacher, as a gift the god of reincarnation sent him the "Old Man Teaching System" How is he to adapt?!

System: Host must teach the children like an old man would!

James: What? Okay, the square root of-

System: No! Explain it like an old man!

James: ???

Follow his daily life of being an old man, doing things ranging from tending to his garden, protecting his lawn from children, and teaching annoying teens.