As a member of the hero's party, she has contributed to leveling up with her skills, but when she is no longer needed, she is exiled, and the ``trainer'' Aroze returns to her hometown where budding adventurers gather. Deciding to live a quiet life for the rest of her life, he is visited by a young adventurer girl who shows no signs of growing up, and before he knows it, he decides to help raise her. The strongest fantasy begins without realizing it, between a friendly all-purpose trainer and his friends who have become the "strongest" without realizing it!