Lucifer's Descendant System - Chapter 3: Task

To rise from defeat; to revive amidst the dissipation.

Anyone who could construct a stable Spell Model could become a Wizard — that was the Wizards’ ultimate secret! Having been given a new life as the son of an aristocrat and armed with a super quantum computer from his past life, Spell Models came as easily as breathing to Merlin. With this overwhelmingly huge advantage, would Merlin become the greatest Grand Wizard of all time?

- Description from Novelupdates

After a god screws up and accidentally takes high schooler Shou’s life, he offers him reincarnation with a gift to make up for it. Shou asks to retain all his old memories for the new life. Shou is reborn as Will, a noble’s son in a world where magic use is common and involves knowledge of kanji characters. With all his memories, he’s a brilliant toddler, and when he experiments with magic, he finds that he has an amazing talent for it! What’s more, though he was smart but unloved in his old life, in his new life he has a mother and a father who both love him deeply. His future as Will is looking very bright and cool!

Talented in Magecraft but useless in physical combat?

Can summon 10,000 Servants but can he defend the rear by himself?

I will say just one line in reply:

“That will not be a problem!”

This is the tale of a young man who obtained an enshrined miracle.

“As long as I have my familiars, I am undefeatable!”

- Description from Novelupdates