Matarou has always been in love with Mikoto Takashiki. One day, he confesses to her and they begin dating. She brings him over to her house to make him dinner. While he's waiting, he goes around the house and finds scraps of her diary. As he collects more pieces, he slowly realizes that there may be something wrong with Mikoto.
Not to be confused with either Yume Nikki or Mirai Nikki.
Tropes associated with Mikoto Nikki:
- Abusive Parents: Mikoto's parents were the ones who pushed her over the edge and into her psychotic behavior.
- Antagonistic Offspring: Mikoto snapped and locked up her parents in her closet. She fed them and tried to "take care" of them. They called her a demon child one day and she left them in the closet without food for a week. This killed her father and was slowly killing her mother.
- The Bad Guy Wins: Technically, even in the true ending. Mikoto isn't really bad per se, but she's not someone who should be out in society without seeking professional help.
- Big Bad: The titular Mikoto is Yandere towards Matarou and wants to trap him in her house.
- Broken Bird: Mikoto suffered from abuse and neglect from her parents. It got so bad that she snapped and ended up unintentionally killing them.
- Broken Ace: Mikoto is described as having "both beauty and brains", is admired by many boys in her school, has the highest grades in her class, and excels in pretty much anything she partakes in. It's revealed that she wasn't always like this, and worked really hard to be the person she is now just to gain acceptance from her abusive parents and peers. This eventually drove her mad.
- Curtains Match the Window: Mikoto has dark blue hair and eyes while Matarou has brown hair and eyes.
- The Dog Bites Back: After putting up with their abuse, Mikoto rose up against her parents and locked them in her closet.
- Driven to Suicide: After she unintentionally killed her parents, Mikoto thought about killing herself because she saw no reason for living. In the True End, Matarou is worried that she will go through with it if he leaves her alone.
- Dude Magnet: Mikoto is very popular at school with the guys. She even brags about her popularity in her entries.
- Dull Eyes of Unhappiness: It's kind of hard to see them, but it's implied Mikoto's eyes turn into this after Matarou goes in her closet.
- Earn Your Happy Ending: The True Ending ends with Matarou accepting Mikoto despite the fact she killed her parents. They become a couple and Mikoto slowly becomes a more functional person thanks to Matarou's love and support.
- Feminine Women Can Cook: It's noted the Mikoto is an excellent cook. The whole scavenger hunt starts while she's making dinner for her and Matarou.
- Freudian Excuse: Mikoto suffers from low self-esteem due to her trying to impress her parents. She doesn't feel like anyone understands her since she's constantly hiding behind a smile.
- Happy Ending Override: Full Bokko Youchien and Dice Psycho reveal that Matarou married Mikoto and had a son, Mitarou. In order to protect her, he took the fall for her crimes, culminating with Matarou being arrested on death parole and leaving Mikoto to raise little Mitarou as a single mother.
- Hell Is That Noise: There are few instances where there's a garbled sound effect.
- I Just Want to Be Loved: Mikoto just wants someone to love and understand her.
- Kick the Dog: There are options to be mean to Mikoto such as saying you hate black tea, tell Mikoto to redo the meal or refuse to hold her hand. These options don't affect the final choice.
- Madness Mantra: "break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break break"
- Mood-Swinger: Mikoto's entries go back and forth between being cheerful, sad, or crazy.
- Multiple Endings: Two Bad Ends and one True End. There's another ending available if the player chooses to enter the closet without getting the flashlight.
- No Flashlight: Matarou enters the closet and is unable to see anything. Despite that fact, Mikoto hits him over the head from behind and cheerfully announces that he should've watched his back in a dark place like this before coldly stating she's going to kill him.
- Bad End 1 - From Behind: Matarou runs away from Mikoto, managing to escape her house. Despite running away a far distance, though, she immediately catches up and apprehends him. The ending is left unclear, but it is suggested that Mikoto either killed him or brought him back to the house to be locked away in the closet.
- Bad End 2 - What You Wished For: Matarou decides to stay with Mikoto, to her surprise. She tells him that she will prepare lots of food for him... before promptly closing the closet door and locking it, suggesting that he will share the same fate as Mikoto's parents and Yukimaru.
- True Ending: Matarou hugs Mikoto, causing her to be moved by Matarou's actions, and she starts apologizing for what she has done. Months later, she and Matarou are still together, both shown playing in the snow. Matarou fondly notes how Mikoto's behavior has improved since he had accepted her.
- Red Eyes, Take Warning: Mikoto's eyes turn red when she confronts Matarou about getting into her closet or during her bad endings where she decides to kill him.
- Stepford Smiler: Mikoto is implied to be Type A at first, always hiding her problems with a laugh and a smile. But because of her Freudian Excuse, she's really a Type C.
- Too Dumb to Live: Matarou decides to continue the "scavenger hunt", even after reading Mikoto's darker entries.
- "Well Done, Daughter!" Girl: All Mikoto wanted from her parents was to be praised and loved by them. However, because they were neglectful and abusive, this led to her becoming mentally unstable.
