Eiyuu Kyoushitsu no Chouetsu Majutsu Shi: Gendai Majutsu wo Kiwame Shi Sha, Tenshou Shi Tenshi wo Shitagaeru (Light Novel)

Calgrande is a magical academy that the nobles and elite magicians attend. A world of magical fundamentalism, where the strongest talents for the national military gather. Yuuma, a genius magician who once before saved another world, died and reincarnated to this world, is now attending this academy for the sake of achieving a certain goal. Yuuma who is considered the hero candidate of this generation was living happy days with his genius sister in law who is also a brocon, as well as with his other sister in law who is a spoiled angel. However, all of this changed during a extracurricular trip to the demon world. When the evil parts of this world bare their fangs against his precious sister, the magician from the otherworld is unleashing his true power!