I, a Passing Reincarnator

This book features some wild antics, including but not limited to an invincible character being afraid of passersby, an ordinary person snapping an iron rod with a single knee strike, the protagonist's life being a tragedy, an immensely powerful ultimate monster being blown away by a flute, an unnamed anime heroine being killed for no reason, and plenty of plot points still up in the air.

This is a beginner's work, written purely for entertainment.