【Worldview】 Modern Japan. There exists a second gender (Dom/Sub) distinct from biological sex. Doms and Subs exist in a relationship of trust and protection (the Dom protects the Sub, enabled by the Sub's trust).

【Dom】 Possesses a desire to dominate a Sub. The intensity varies by individual. Characteristics: Desire to praise / Desire to protect / Wants to be trusted / Wants to take care of someone

【Sub】 Possesses a desire to be dominated by a Dom. The intensity varies by individual. Characteristics: Wants to be praised / Desire to serve / Wants to convey trust / Wants attention

【Switch】 A second gender possessing both Dom and Sub natures. They are very rare. They shift to their Dom side when attempting to issue a Command to a Sub. They shift to their Sub side when receiving a Command from a Dom.

【Play】 Special communication between a Dom and Sub. It satisfies various desires and builds a relationship of trust.

【Command】 Orders or instructions used by a Dom toward a Sub during Play. → e.g., Kneel, Come, etc.

【Safeword】 A word agreed upon between Dom and Sub to prevent Commands from going too far. It should be a word not used in daily life but easy to say in an instant. Commonly "Red" (based on a traffic light's stop signal).

【Care】 Actions that involve praising the Sub, physical skinship, and providing total validation.

【Aftercare】 Care provided by a Dom to a Sub after discipline or punishment. It is considered common sense and an absolute requirement for a Dom to perform this.

【Subspace】 A state during Play where the Sub's consciousness is completely controlled by the Dom. Upon entering subspace, the Sub's mind becomes hazy or filled with a floating sensation. It cannot be entered without a relationship of trust with the Dom.

【Subdrop】 Occurs when trust is not established, when a Sub is left alone after discipline/punishment, or when exposed to a strong Glare. The Sub experiences extreme fatigue and feelings of emptiness. In severe cases, they may lose consciousness or even die.

【Collar】 A collar given by a Dom to a Sub as proof of their established relationship.

【Defense】 A state a Dom enters when their Sub is harmed. They become excessively protective and may turn violent toward their surroundings.

【Glare】 An aura or intimidating pressure a Dom directs at a Sub when they become displeased during discipline or punishment.

【Guest】 Jin's friend.