Milulun, originally named Run, transitioned from a human teenager to an LRIG card. She exhibits a bright, cheerful, and bubbly personality with ditzy tendencies, often blurting out thoughts without filtering them. This habit frequently leads to unintentional teasing, especially concerning others' embarrassing secrets or past actions. Despite occasional insensitivity, she genuinely cares for those close to her.

In *selector spread WIXOSS*, she served as Akira Aoi's second LRIG. Their relationship featured friendly antagonism: Akira frequently yelled at her while Milulun teased or ignored Akira in return. During battles, Milulun expressed initial excitement about partnering with a "cute" Selector but became intrigued by Akira's personality, particularly her obsession with Urith. Milulun openly teased Akira about private moments, like Akira's emotional outbursts over Urith, provoking Akira's anger. Despite the friction, Milulun later admitted liking Akira for her true self, acknowledging both her flaws and positive traits like passion and vulnerability. After Akira's third loss to Urith, Milulun reverted to human form and was last seen disembarking a bus.

The *Selector Girly☆Talk Drama Track* depicted a post-battle reunion between human-form Milulun and Akira. Milulun fondly recalled their partnership and reminded Akira of her real name, Run, when forgotten. She playfully recounted Akira's past antics involving Urith, causing Akira embarrassment. When Kiyoi Mizushima joined, Milulun enthusiastically inquired about their battle chemistry, leading to further teasing about Akira's losses. Despite the banter, Milulun affirmed her affection for Akira, listing her admirable qualities before their heartfelt parting.

In *Lostorage conflated WIXOSS*, Milulun reappeared as an LRIG, forcibly reassigned to Akira for new Selector Battles. Her design evolved to a more mature appearance with longer blue hair in a side bun and an elaborate star-adorned dress. During Akira's first battle against Kiyoi and Piruluk, Milulun's coin-bet skill introduced random effects, disrupting prediction-based strategies. They lost, resulting in Milulun's capture by Kiyoi. Kiyoi later deployed Milulun in a rematch against Akira; activating her coin skill wiped out Akira's life cloths, directly contributing to Akira's erasure after Kiyoi's final blow.

Milulun's relationship with Akira blended antagonism with underlying loyalty. She initially found amusement in Akira's volatile emotions but developed sincere appreciation for her authenticity. Her human form featured matured blackish-grey hair in a large side bun and a green-and-white school uniform. As an LRIG, her abilities centered on unpredictable coin-bet effects, making her a tactical wildcard.