Reincarnated as the World Tree

I was just a NEET, but one day I went to a convenience store and got killed by a robber. After that, a goddess suddenly appeared, took a liking to me, and I was successfully reincarnated in another world—but I came back as a "plant" of all things...! What's more, for some reason, every monster and human I meet is calling me "Lord World Tree"!? (Source: kuragebunch, translated) *Note: Three extra chapters are included*.