Nekomata, also known as Nekomaru, is a 300-year-old bakeneko serving as Ryunosuke Sakamoto's companion. He journeyed from Shanghai to Kyoto seeking legal registration under contemporary monster licensing laws. His core ability involves transferring one of his nine lives to resurrect deceased individuals, frequently reviving Ryunosuke after accidental deaths as a testament to steadfast loyalty. This power occasionally triggers unintended consequences, such as reviving Ryunosuke in a female body following a fatal soap-related mishap, creating temporary identity confusion.

Nekomata displays a timid, cowardly personality, often whining or cowering during peril. This trait intensifies due to his role as a test subject for Gennai Hiraga's experimental inventions, which routinely subject him to painful or humorous outcomes. Despite his fears, he harbors genuine affection for Ryunosuke, actively supporting his happiness and intervening in critical moments. In the series finale, he sacrifices three lives to resurrect three deceased heroines, demonstrating willingness to endure personal loss for others.

He engages in recurring comedic and plot-driven scenarios, including forced exposure to Gennai's hazardous gadgets and fantastical gags like an inflating body that bloats him balloon-like—a visual later adapted in official pachinko games. Throughout these events, his protective instinct toward Ryunosuke drives his actions, cementing his dual role as comic relief and pivotal supernatural ally.