Miki Nikaidō is a free starting character in Mahjong Soul, available since the game's launch. This mysterious and intelligent female mahjong player exhibits a flirtatious and unpredictable nature. She owns a pet hedgehog and collects gorgeous gems, her preferred gifts; gifting diamonds grants bonus bond points.

Her bond progression requires 50,000 points across five hearts, needing specific items for full bond: 10 Spheres of Love, 10 Spheres of Wisdom, 5 Hearts of the Ocean, 10 Wishing Stones, and 100 Star Dust. She possesses multiple unlockable outfits: a default appearance, a full bond outfit, and event-exclusive costumes like "Halloween Party" and "Spring Celebration."

Increasing bond levels unlock in-game stories: "Tenhoukaku" (Level 1), "Agate" (Level 2), "Mahjong Competition" (Level 3), "Dinner" (Level 4), and "Date" (Level 5). An additional story, "Experience," becomes accessible after achieving full bond.

The character draws inspiration from real-life Japanese professional mahjong players, the Nikaidou Sisters. Her name "Miki" fuses the sisters' names: Rumi Nikaidou (elder) and Aki Nikaidou (younger). She stands 168 cm tall, was born on February 14th, is 24 years old, and has blood type A. Miki Nikaidō appears as part of the ensemble cast of Jyanshis in the anime "Mahjong Soul Kan!!".