Black Paradox

Four people intent on killing themselves meet through the suicide website Black Paradox: Maruso, a nurse who despairs about the future; Taburo, a man who is tortured by his doppelganger; Pii-tan, an engineer with his own robot clone; and Baracchi, a woman who agonizes about the birthmark on her face. They wander together in search of the perfect death, fatefully opening a door that leads them to a rather bizarre destiny...

(Source: VIZ Media)

Included one-shots:
The Licking Woman, Mystery Pavillion