Yuu is now living with his new big sister-an inhuman being he encountered in his uncle''s basement! It''s the middle of summer, and the two of them are enjoying their days, playing in the garden, splitting watermelons, and taking naps together. Life as a family is simple yet pleasant for these unlikely siblings. Little by little, their bond seems to grow stronger, but Yuu has got an uneasy feeling he just can''t shake...