My Girlfriend Is a Colossal Cutie Vol 1

From the Yen Press edition

Who says a short king can’t find love? In fact, not only does Amane have an adorably cute girlfriend who’s got a smile that lights up the whole world, she also happens to be the tallest person in class! It may be a challenge for these two goofballs to work around their height differences—especially since they’re keeping it on the down-low to avoid being teased about it—but with a positive attitude and a lotta love, this height-gap romantic comedy will leave you wanting more!

Source: Yen Press