TV-Series
Description
Kazuki Yuiga is the younger brother of the protagonist Nariyuki Yuiga and the twin brother of his sister Hazuki Yuiga. He is a student at Ichinose Middle School and is the second son and youngest child of the Yuiga household. Kazuki is depicted as a young boy with short hair and striking aubergine-colored eyes.

His personality is characterized as energetic and mischievous, yet he is also thoughtful and perceptive. His perceptiveness allows him to pick up on subtle emotional cues, particularly the romantic tension between his older brother and the girls in Nariyuki's life. He often uses this insight to playfully tease Nariyuki, acting as a cheerful instigator in the family's dynamic. Despite the family's financial struggles, Kazuki maintains a bright and cheerful demeanor and is willing to help with household chores.

His primary role in the story is as a supporting family member who frequently interacts with the main cast. Alongside his twin sister Hazuki, he often tries to match Nariyuki with one of his female acquaintances, focusing his attention on securing a partner for his older brother. He and Hazuki are usually seen together, acting as a mischievous pair who enjoy embarrassing Nariyuki. Kazuki has a habit of asking when his brother will find a wife.

In terms of relationships, Kazuki shares a close bond with his twin, Hazuki, and together they look up to their older brother and older sister, Mizuki. Because their father passed away not long after Kazuki and Hazuki were born, and their mother is often busy with work, the older siblings take on significant caregiving roles. Still, Kazuki is noted for being courageous and well-adjusted despite the potential loneliness of his situation.

Regarding his development, Kazuki appears primarily as a young child for most of the series. However, in later chapters, he is shown to have grown into a middle school student where he is active in the karate club. Among his notable abilities, besides his sharp intuition, he has demonstrated an unusual talent for hypnotism, which he once used to calm his older sister Mizuki when she was distressed.