Long ago, he was known as the "Hero of the Nation".

Because of possessing overwhelming magical power, respect turned into awe, the magician Chagall, who was once respected, had his magical power sealed.
The source of his concern while living quietly deep in the forest is that even when his power is sealed, the unceasingly overflowing magical energy cannot be released, accumulating within his body and threatening his life.
He has been able to solve this problem by transferring his magical power to Rousseau, the only cooperative person who visits him from time to time, through contact (sex).
One day, when he was almost attacked by a demon in the forest, he was saved by a young man who was running away from home named Fio.
As a gesture of gratitude, Chagall invites him to his house and during the conversation, Fio expresses the desire to become an apprentice.
Impressed by Fio's kindness, good-looking and potential, Chagall decides to take him on as an apprentice, but...?

A mysterious handsome young man with a lack of magical power and a retired heroic magician who supplies him with magical power (sex).
What will happen to the life of master and apprentice that begins with the coincidence of interests?

(Source: Chil-Chil BL, translated by DeepL)