Mirko, whose real name is Go Kato, is one of the central male protagonists in the anime Ai Shite Knight. He is the older brother of the young boy Hashizo and the sole caretaker of his younger sibling after both of their parents died. To support himself and his brother, Mirko works as the lead singer of a rising rock band called Bee Hive, which he founded alongside his friend and bandmate Satomi Okawa. His life revolves around his music career and his deep sense of responsibility toward Hashizo.

Mirko is portrayed as a cool, somewhat intense, and passionate young man. He has a strong sense of duty and often comes across as gruff or aloof, but this exterior hides a caring and protective nature, especially toward those he loves. He is driven by his ambition to succeed in the music industry, but his priorities are frequently challenged when his personal life becomes entangled with his growing feelings for Yaeko Mitamura, also known as Yakko. Initially, his relationship with Yakko is complicated by a love triangle involving Satomi, but over time, Mirko develops a genuine and deepening affection for her.

His role in the story is that of the love interest and the emotional anchor for much of the dramatic tension. As a musician, his notable abilities include his vocal talent and his presence as a performer, which are central to the band's rise. He also demonstrates considerable resolve and maturity in balancing his responsibilities as a brother, a band leader, and a partner. Throughout the series, Mirko undergoes significant development as he learns to open up emotionally, confront his vulnerabilities, and commit to his relationships, particularly with Yakko and Hashizo. His key relationships include his bond with his younger brother Hashizo, his creative partnership and rivalry with Satomi, and his evolving romance with Yakko, which ultimately becomes the emotional core of the narrative.