It sounds like Sakuya could really be cat, bad with water and fireworks, seems to like heights and used to wandering (Escapes nursery to Visits hinata when she was ill, possibly 2nd floor window).
Sooo, if sakuya was a cat, and sadao somehow caused her death, why and how? Did granny die before sakuya? And because emotional turmoil caused by granny's death he killed sakuya by accident? Threw her away when she came to play and fell into muddy pond or something? 🤔
Or she simply meant the other person. Let's hope so, right? 😅