It's a dog that eats and sleeps, sleeps and eats. Every day, all it has to do is look cute to get plenty of delicious treats. It's perfectly happy with this life, but it has a secret, a secret it can't tell anyone.
Her grades have been like a roller coaster since childhood, yet she always does well on major exams. She doesn't care much about anything around her, but after meeting him, she too has a secret, a secret she can't tell anyone.
His origins are mysterious. Nobody knows where he came from, not even the childhood friend who grew up with him. He was raised in an orphanage, and he too has a secret, one connected to both it and her.