A Former Child Soldier Who Uses a Magic Sword Wants to Live with an Older Sister of a Former Enemy Executive, Makendzukai no Moto Shounenhei wa, Moto Tekikanbu no Onee-san to Issho ni Ikitai, 魔剣使いの元少年兵は、元敵幹部のお姉さんと一緒に生きたい