Reu. The older twin brother. Born a few minutes before Rea. Ages 0–5. At birth: approx. 49cm, 3050g. At age 5: approx. 109cm, 18kg. Characterized by fluffy black hair, gentle dark eyes, long eyelashes, and squishy cheeks. Almost identical to his sister Rea but slightly taller.

Calm and gentle since birth with relatively quiet crying. Finds comfort in being held and is a caring brother who stays close to Rea when she cries.

His favorite is a white cat plushie named "Rei" with a blue bell, always with him since birth.

At age 1, he toddles and speaks baby talk like "Ma-ma," "Pa-pa," "We-a," "We-i," "He-we go," and "Num-nums." He loves holding hands with Rea and playing with blocks.

At age 2, he becomes more cheerful and grows into a kind personality who can share while saying "I do it!"

At age 3, he has a mild rebellious phase but calms down when heard, acting like a protective big brother.

At age 4, he becomes social and responsible, always trying to help others.

At age 5, he can handle his own chores and basic writing, growing into a reliable boy who protects Rea because "I'm the big brother!"

A kind-hearted boy who loves cats and still sleeps hugging "Rei."

Rea. The younger twin sister. Born a few minutes after Reu. Ages 0–5. At birth: approx. 48cm, 2900g. At age 5: approx. 108cm, 17kg.

Soft black hair, large dark eyes, and crescent-moon smiles. Almost identical to Reu but very expressive and emotional.

A clingy child who cries energetically when hungry and flails her whole body when upset or sick.

Her favorite is a white cat plushie named "Ai" with a pink bell, always with her since birth.

At age 1, she toddles and speaks baby talk like "Ma-ma!", "Pa-pa!", "We-u!", "Ai!", and "Meow!", constantly running and falling.

At age 2, she grows into a high-energy girl full of curiosity and chatter.

At age 3, she hits an intense rebellious phase with lots of "No!" and "Rea do it!", though she recovers quickly.

At age 4, she enters the "Why?" phase, asking questions all day long. By age 5, she is a sun-like girl who loves singing, dancing, and drawing. She trusts Reu most of all and sleeps peacefully hugging "Ai."