The Disappearance of Hayakawa Ryoko

The Legend of Bateren Island

The Ferris Wheel of Death

The Mysterious Kappa of Tenkoji Temple

The Classmate Who Was There But Not There

The Tragedy of Kugisawa Mansion

Bonus Chapter: Hayakawa and Kishida

The Cherubic Ghost

Capture the Tsuchinoko on Mt. Urakami!

The Puppeteer

The Actress's Secret

The Ghoulah Box

The White Hand

Memories of a Snowy Day

Bonus Chapter: Shikino and Kishida

Night of the Slayer

Night of the Slayer II

Angel-sama

The Clayman Cometh!!

The 3rd Annual Naranara Festival

The Haunted Tunnel

Day of the Pig

The 1st Occult Experience Presentation

Murder Mansion

The Hepalo Warrior Statue

Island of the Returners

The Path of the Dead

Interview with the Human Spirit Path

Yomotsuhirasaka of the Mind 

The Wriggling House

In the House of Evil Spirits

The Ominous Painting Part 1

The Ominous Painting Part 2

Massacre Village

Ghost Link

The Lost World Part 1

The Lost World Part 2

Ghost Kiss

Aoba Legends: The Bloody Go Board

Our Zombie Teacher

The Ghosts of Rabbit Island

The God Project

The Shadowless Guardian

The House by the Sea

The Book of Magic Part 1

The Book of Magic Part 2

Ghost Knife

Chocolinne: The Irresistible Sweet Part 1

Chocolinne: The Irresistible Sweet Part 2

The Five Ghosts

Poltergeist New Town

The Wild Night of the Gods

The Ghost Nextdoor

Night of the Cats

A Familiar House

The Antagonistic Ghosts

Ghost Requiem Part 1

Ghost Requiem Part 2

Ghost Requiem Part 3

At My Great-Grandmother's Wake Part 1

At My Great-Grandmother's Wake Part 2

The Dreams of a Psychic Idol

Night Crawler

Legend of the Red Sand

Takeo's World

Her Own Personal Hell

The Locked Storeroom

My Bloody Night Game Part 1

My Bloody Night Game Part 2

My Bloody Night Game Part 3

To Touch a Ghost

The Beast Within

Ghost Rising

Karogawa Juzaburo's Dream

An Idol in Bloom

The Occult Club's Last Summer Part 1

The Occult Club's Last Summer Part 2

Aoba Apocalypse Part 1

Aoba Apocalypse Part 2

Aoba Apocalypse Part 3

Jun Kishida is a sickly high school student who can see dead people. One person in particular is following him around: his childhood friend Ryoko Hayakawa. Even after he uncovered the truth behind Hayakawa's death, she stayed by his side. As he and his classmates get into even more strange and mortally dangerous situations, Hayakawa's spirit quietly aids him. 
(Source: MangaHelpers) 
Included one-shot: 
Volume 4: Yumi-chan Kitan