Congratulations on your 2nd birthday celebration, Haru-kun! I wish you good health and development (physically and intellectually), happiness and a lot of fun playing with your sister Yuzu-chan!
The Google-translated title says Haru-kun is in the 'terrible-two' phase, and refuses to change to festive clothes for his 2nd birthday celebration; this makes his parents depressed (likely, jokingly)! Haru-kun has good interactions with his grandparents who bring many gifts for him. He practices reading books and putting together puzzles, with her encouragement. Maybe he should spend more time at his grandparents' place during the daytime when Yuzu-chan is at kindergarten!