|Appearance||Period 2: The Bonds Of A Curse|
|Fate||Deceased - Abused by Sakahara|
Kotaro is scrawny dog who was said to be small, implying he is a young or a small breed. He has pointed ears and small eyes.
Like any other young dog, Kotaro was friendly and loved attention. He could be mischevious at times but he didn't appear to mean any harm. Oddly it appeared that he was able to tell how people were by the way he reacted, such as wagging his tail around Kurosawa, or growling and looking unhappy around Sakahara.
As Kotaro returned to his bed Ai and her friends made, she recalled finding him a few months back one rainy day. He had taken shelter beneath a large bush and seeing how dirty she was, she picked him up and got him clean, and with permission from their teacher she agreed to let them keep him. Ai spent a long time with Kotaro, working on a nice dog house for him and spoiling him with yummy food and treats, and even bonded with Kurosawa, who she had tried to approach prior to this. In this time she noticed he had an injury but didn't pay it much attention, having assumed he gotten it from his careless wandering around.
But then one day, Ai returned to school to learn that something happened to Kotaro as she saw his destroyed home and bruised corpse. She remained behind, too shocked to say anything until overhearing Sakahara and his friends approach, where she found out he had been the cause of it. He saw abusing the poor dog as a way to relieve stress and had put rope on its neck, tying it to his bike and forcing it to run after him until it became too much for the dog. Then he brought it back. Hearing this, Ai went and got a voodoo doll from Kurosawa and made Sakahara pay, having given him a similar fate without a sign of guilt or remorse.
With Kotaro avenged she and Kurosawa prepared a grave for him.
- He peed on Ai twice during the story.