Create an image of a young, cheerful elementary school boy with short black hair and a bright smile, wearing a casual blue t-shirt and shorts. Next to him, depict a small, adorable hippopotamus with a friendly expression, sitting upright. The setting is a sunny park with a few trees and a playground in the background. The characters are from the Japanese manga and anime series 'Shonen Ashibe --cref <https://s.mj.run/7lKb8zc8ypM>