Path of the thunder emperor ~Become the Strongest in Another World with [Thunder Magic] which Only I Can Use! is a Manga/Manhwa/Manhua in english language, REINCARNATION series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

What I have in my hand is "thunder magic" that only I can use...! The adventure story of a boy who was reborn as the one and only lightning magician to become the strongest in a different world begins now!