Kasou Ryouiki no Elysion - Volume 1, Chapter 2 - First Suppression

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

I became the childhood friend of the protagonist in a novel. The childhood friend who died from taking drugs.

After reincarnating as Zhou Xuanji, the prince of an empire, he thought that he would be able to live a worry-free life of luxury. He did not expect to be involved in a rivalry with the Empress herself, who forced him to escape from the palace.

A 34-year-old NEET otaku, chased out from his house by his family, found that his life is reaching a dead end. He then recalled that his life could actually have been much better if he had made better choices in the past.