Seek some light novels of modern fighting harem men.

Monty black rabbit

High school DxD

Ferdinando Campione

Master and maid's adult

Arrive with her at my night

Sweet complete contact

First love electric shock magic

Black Strika

The Battle City of Semislav

Can a fool save the world?

Trigger a world crisis

S egg

Material ghost

Rent a magic messenger

I've only seen these. One by one, it's really troublesome.