Kugaya is a teenager who lives with his aunt, Sakuri.
The kendo coach at his high school, Narugami, has been after him to join the kendo team; but when he meets the new girl, Takemi, his life takes a supernatural turn and he is thrust into an epic battle with the demonic "Intruders".
Reincarnation... buried memories... the Holy Sword... "Himuka"... and the Clan of the Swordsmen... it's all too much for a high school student to bear!

A story focusing on a group of college friends, and their lives. Each chapter focuses on a different friend, and their relationships with various other characters.

From MangaHelpers:

One of the surveillance ships of the company Ferret went missing for some time. Once the ship was found, all 115 members aboard the ship were completely missing. No trace of their existence was found aboard the ship.

Masato's sister works for Ferret, and he was tasked to bring her supplies for the upcoming work to investigate this mysterious ship that returned without her crew. He meets a beautiful girl named Uto at the company, who also had a brother that worked for Ferret and went missing inside the ship. Now Masato and Uto must embark on a mission to discover the mysteries of the unknown island where the missing crew has been left. [DrCoke]

Kyouhei, after moving away to Tokyo from his old town to get away from the events that happened, is on a goukon with his friends, including his old neighbor, Shiba. After drinking for a whole night, he and Shiba discover a dead, bloody, body in the elevator. He is told by his younger sister, Utao with her doll, that Aki, an old friend, and his doll, are the culprits responsible.