Ai Mikami

Ai Mikami is the Seventh diary owner, which is shared with her boyfriend Marco Ikusaba. Devoted to Marco, Ai and he shares the "Exchange Diary", which the couple use to keep an eye on each other at all times. They wish to become God so they can stay together for an eternity.

Personality
Ai is a beautiful, blue-haired, purple-eyed woman, and the long-time lover/wife of Marco Ikusaba. From a young age, she loved Marco after he befriended her and gave her a family after she was abandoned by her parents as a child. She is very devoted to him, and together they form a strong battle couple. Ai is implied to be a flirtacious person, since the Apprentice Diary she gained, the "Flirting Diary", involved identifying the men she would flirt with. She seems to be at peace with Marco's constant fights, actually being a skilled knife thrower. She keeps a collection of throwing knives in her jacket, and cn throw them with pinpoint accuracy. However, she only has so many and is bamboozled when Yuno Gasai is able to deflect them all.

Despite participating in the survival game, Ai and Marco have morals. Ai takes sympathy towards Tsubaki Kasugano, the Sixth diary owner, although she expresses the knowledge that sooner or later that Tsubaki would turn into an enemy if she and Orin Miyashiro had helped her with her troubles. Ai and Marco also refuse to take a life that they do not plan to, treating the wounds of Hinata Hino and Mao Nonosaka who Ai had injured with her knives.

Marco and Ai share the "Exchange Diary", which appears as two mobile phones. The diaries allow Marco and Ai to predict each other's movements, and can protect each other when in a fight. If one of the diaries is destroyed, the other owner remains alive.

History
Fourteen years ago, Ai was abandoned by her parents at the Sakurami Tower and was told to wait for them to return. By sunset, Ai realised her parents had gone and cursed the day as being the worst of her life. It was at this point that Marco approached her for the first time, having observed her for most of the day. He told her that if that day was her worst day, than the next day would be better. Marco invites Ai to come live with him in the orphanage of Kamado Ueshita, who would become the Eighth diary owner. Ai accepted.

In high school, Ai started her first year following Marco around, having grown quite attached to him. Marco objected to her following him around all the time, but he eventually relents. The two grow close, and were implied to be dating despite Marco being a street fighter. The two eventually revisited the Sakurami Tower, Ai revealing she had her own diary based around Marco, which he suggested should focus on something other than him. The two visit the tower's chapel, Ai revealing she wants to marry Marco in the chapel.

Later, Ai finds a letter requesting a meeting in an abandoned factory. Assuming Marco sent it, Ai goes to the factory only to be ambushed and sexually assaulted by three boys. Marco arrives, angrily beating the boys and kills one of them when they draw a knife. Returning to the tower, Marco nearly kills himself with the knife but is stopped by Ai, who promises to emotionally support when he is in pain. Both declare their love for one another, kissing atop of the tower.