World Teacher – Isekaishiki Kyouiku Agent

Story:

Training is conducted according to the laws of the alternative world. Sirius was once a better agent. He sacrificed his life for friends and was able to be born again, but in another world. Not having fully trained his disciples in the ordinary world, he took the luggage of knowledge and experience and decided to start training those around him. Thanks to this, he abruptly changes their entire lives by 180 degrees. For them, he's a teacher, and for others, something more… Learn the manga sequel.