Yumekui Danjon
ゆめくいダンジョン
A timid girl named Katori has a crush on a boy in her class, Tooru. After her elderly sheep dog, Jon, passes away, it is discovered that he was a Baku, a creature that consumes nightmares. He had transformed into a dog out of boredom, and his final goal was to have Katori and Tooru fall in love, which would allow him to be reborn as their child.