Since I Became Healthy After My Contract With a Weapon Was Broken, I Decided To Live For My Happiness

Differing from elves and beastmen, humans cannot use magic. Due to this peculiarity, they have mana stored inside their body. If the mana present inside is too large, they will be afflicted by an illness called Mana-Poisoning. Suffering from this disease since childhood, I was unable to perform much physical activity. My family was the Leslie Count household who hereditarily performed knightly duties. They were cold and indifferent to me. This was true even for the sword Katrina who was contracted to me. She is a tool called Servant which possesses a personality, using such tools even human beings will be able to cast magic. By binding a contract with her, I somehow managed to live this long...