|Appears||Week 1 (Debug)|
Mai is the fifth student to be introduced as an Easter Egg.
Her first look had pink hair that was a recolor of Sakyu Basu's hair but longer, reaching down to her hips. Mai's eyes were the same shade of pink as her hair. She had a very large bust size, set at 2.
As of the January 1st, 2016 Build, her hairstyle went below her knees. On her left and right side she had more hair, but most of it went to her elbow. The rest closed in on her chin. Her bangs were cut short and met together at the middle. Her bust size had been decreased to 1 so her hair couldn't clip through her breasts. As of January 16th, 2016, YandereDev stated that Mai Waifu would get new hair in the future.
As of the February 8th, 2016 Build, her hairstyle was of average length and was magenta. Her hair became longer and her bust sized increased to its original size of 2 as of the February 15th, 2016 Build.
As of the February 17th, 2016 Build, her eyes now gradually change their color, cycling through every color of the rainbow, every moment of the day.
In the September 1st, 2017 Build, Mai's eyes were slightly slanted downwards, her eyes would only take this appearance while she was wearing the default uniform. As of the September 2nd, 2017 Build, her eyes have been changed back due to problems with her model.
Among the personas currently implemented in the game, she is a Loner. If she sees a corpse or witnesses a murder, she will run home and call the police. She cannot participate in physical fights against murderers. Because she is shy, she will hide her face if Yandere-chan aims her camera at her.
She is described in her Student Profile as "kawaii", "moe" and "deredere" by her admirers. She prefers to spend most of her time alone, fantasizing about her loved one.
At 7:05 AM, Mai enters the school grounds. She walks to her locker at 7:10 AM and changes from her outdoor shoes to her indoor shoes. At 7:15 AM, she walks to the rooftop and gazes out from the northern side.
At 8:00 AM, Mai walks into Classroom 3-1 and sits at her desk. She starts her morning classes at 8:30 AM, and leaves to go to the rooftop at 1:00 PM.
Mai walks back to class again at 1:30 PM and participates in cleaning time between 3:30 PM and 4:00 PM. Afterwards, she heads to her locker and changes from her indoor shoes to her outdoor shoes, then she lingers there until 3:50 PM, then walks home.
Unknown Independent Game Developer
She has sworn her heart to an independent game developer who lives overseas. Mai Waifu prefers to spend her time alone, fantasizing about her loved one.
- Occasionally, Mai's hair clips through her body.
- If Mai is kidnapped, one of her eyes will be grey, while the other will continue cycling through the rainbow.
- The game's warning referred to Mai, saying that the game contains "busty pink-haired schoolgirls". This warning was later removed because YandereDev said that it was "cringey".
- Mai Waifu has many admirers, but no stalkers.
- She was implemented in the November 15th, 2015 Build.
- She resembles YandereDev's "appearance" on Twitter, where he described himself as a sixteen year-old Japanese school girl with pink hair, large breasts, and rainbow eyes.
- Her name is a pun on the Japanese phrase "mai waifu" (マイ ワイフ), a term adapted from the English "my wife". Some Japanese husbands will refer to their wife as "mai waifu". When used in Western cultures, "waifu" means a person's favorite anime or manga character who is female.
- Mai Waifu and Midori Gurin's Student Profiles were not updated to match their second and third hairstyles given to them in the January 1st, 2016 Build; however, this was updated as of January 15th, 2016.
- Mai Waifu makes a small cameo in the Gaming Club's stealth game, being stalked by Oka.
- If K is pressed at the debug menu, Mai will appear as a mindslave instead of Musume.
- Mai may become a distraction for male students in the future.
- In LoveSick Mode, Mai's name is changed to Mai Wakabayashi.
- YandereDev thinks that Akane Toriyasu has more admirers than her. 
- Mai might be removed from the Gaming Club in order to make the Gaming Club have 3 males and 2 females.