Asuna's manga / #Nobility(3)

He was a sage in his past life and was the only one who had a contract with spirits from all 4 elements. He died lonely with only his spirits for company at the age of 92 and when he woke up he was the 1st prince of his country. A neglected, super weak not healthy introverted short prince. He was not respected by his classmates because of his weak body and personality but when the sage woke up he started making friends specially with the help of his spirits. He discovers that he had been on the body of the prince since he was born but he was sleep until the prince died from poisoning (by the current empress). 2 people know his true identity of the sage, both were disciples of him, one is a necromancer who went down the wrong path, and the other is a spirit master with 2 spirit contracts. They're currently trying to solve the mystery of the ghost of the academy.