I'm looking for a manga where the protagonist is a boy (teen?) who fights monsters with his artificial partner.

• the monsters are created when 2 "seeds" (inside a persons body) come in contact with eachother, making the "hosts fall in love"
• the protagonist doesn't beleave in love and refuses to except any evidence of love.
• the partner is a manmade "container" to store the defeted monsters
• the partner is female, wears a bunny ear headband, and carries around a giant stuffed bear (bunny?)
• she would be described as a loly in her looks and dress
• the protagonist wears a hoodie bunny ears on it
• he fights with a weapon (scythe) made from his blood/essence?
• he works in a company where fighting these monsters is their job
• he suffers from a tramatic past and goes haywire a few chapters in.
  [/m][spoiler]

It's Kyouai Catastrophe.