The Stony Cat, also known as the Cat God, functions as the Tsutsukakushi family deity. Possessing near-omnipotent wish-granting power, it typically fulfills wishes in two ways: transferring an unwanted trait from one person to another who needs it more, or granting wishes in unintended or distorted ways. However, it can bypass these rules to grant wishes precisely without adverse consequences when it chooses.

Initially found as a small wooden statue under a hilltop tree, it sits expressionless with raised front paws beside its head. Its appearance changes with wish fulfillments; for example, it begins to smile after taking a character's expressions, the smile widening before vanishing when the traits are returned. A second, larger statue resides in the Tsutsukakushi family storehouse, granting wishes unconditionally. A third, smaller statue comes into another character's possession.

Mischievous yet fundamentally benevolent, the Stony Cat is dedicated to safeguarding the Tsutsukakushi family. It experiences human emotions like vulnerability, embarrassment, boredom, and loneliness, actively intervening in human affairs to alleviate these feelings in itself or others. Its wish-granting drives the central plot, altering main characters' personalities—such as removing one character's ability to hide perverse thoughts and another's capacity to express emotions—leading to interconnected struggles among the recipients.

Its motivations reveal complexity. It manipulates circumstances not only to fulfill its wish-granting role but also to address its own emotional needs, like combating loneliness through human interaction. Its involvement extends beyond single transactions, influencing ongoing character development and relational dynamics, including conflict resolution from earlier wishes. Its origins as a family god tie into broader familial backstories, particularly concerning the Tsutsukakushi sisters' memories and their mother's legacy.

While enabling supernatural plot changes, the Stony Cat is defined by its paradoxical nature: a powerful yet emotionally susceptible entity operating by self-defined rules, alternately adhering to or subverting its wish-granting patterns based on situational or emotional considerations.