Ghost

Ghost is a ghost that visits Kyuu-chan's house occasionally. He first appeared in Chapter 129, "Chill".

Appearance
The Ghost resembles a small floating sheet with nothing underneath, along with eyes and a tongue sticking out.

Kyuu-chan
The Ghost initially appears to try and scare Kyuu-chan, but when his efforts fail they become friends instead.

When the Ghost entered a scaring contest, Kyuu-chan came to cheer him on, which psyched him up enough to do his best and win the contest. Afterward, he offered to share the prize, a king crab, with Kyuu-chan and Hinata.

Hinata
Hinata cannot see the Ghost, but he gradually becomes aware of him by watching Kyuu-chan playing with him. While not being able to see or hear him, he makes an extra portion of cake for him to eat (Chapter 204, "Party"). He later realizes he can see the Ghost if he takes a picture on his phone.

Hinata is also capable of touching the Ghost, much to his surprise when he randomly pokes his finger where he thinks he is (Chapter 437, “Spiritual Power Level Up”). He also at one point accidentally throws him in the washing machine, mistaking him for a piece of laundry (Chapter 526, "Casualty").

During Hinata's trip to Hokkaido, the Ghost follows him to keep him company (Chapter 448, "Meanwhile"). Even though Hinata cannot see or hear him, he reveals at the end of the trip that he did notice his presence, and thanks him for accompanying him (Chapter 459, "See You Again Someday").

Trivia

 * The Ghost is cold to touch, as shown when he gives Hinata chills by being nearby (Chapter 268, "Long Time No See"), or making Kyuu-chan's legs go numb from lying in his lap (Chapter 270, "Trembling Lap").
 * The Ghost can eat, but he doesn't need to (Chapter 204, "Party").