So I've read this manga before, It's about a Top 1 Magician. When he died he got reincarnated again and again I think. Then he enters the school as a prodigy and proceed to train 2 girls that tagged along with him. The 1st girl is an Archer, mc taugh her how to make a bow and how to enhance them, I think the other girl is a healer magician? Or something I forgot but she has red hair from what I remember (I may mistaken it cause it's been so long I'm trying to find this manga). Somewhere in the Story they encouter a dragon that turned into a girl and was an acquaintance of mc's past life and this dragon girl uses staff. The lastest chapter I read is them battling a high ranking demons in a town and protecting the kingdom by using runes that is powered by magicians and them battling the incoming demons.
SHIKKAKU MON NO SAIKYOU KENJA - SEKAI SAIKYOU NO KENJA GA SARA NI TSUYOKUNARU TAME NI TENSEI SHIMASHITA