A Failed Submersion

[Book 1] Seiko Tanabe is a bright young girl under the custody of the Armed Detective Agency, her personal guardian being none other than Osamu Dazai, an eccentric detective with an unusual love of suicide.

After meeting an orphan with a powerful ability called "Beast Beneath The Moonlight", she soon finds herself swept up into a maelstrom of danger, deceit, and death as enemy forces begin making their move to capture both her and her new friend, Atsushi Nakajima.

What are the enemies' plans? How is Seiko connected to the Port Mafia? What is the true reason of Dazai's custody over her? And what is the true nature of her ability?

A/N: I do not own Bungou Stray Dogs or any of the images. Credit goes to the original owner.