Doppo Kunikida vs. Shōsaku Katsura

Doppo Kunikida vs. Shōsaku Katsura is a battle fought between Armed Detective Agency member Doppo Kunikida and Shōsaku Katsura.

It happened at an underground subway after Kunikida and Aya investigates the bomb explosion that happened a while ago at the train station.

Prologue
Kunikida is on his way to an anti-terror meeting with the M.P. staff, following a testimony recording of a brutal murder case. Upon arriving at the train station, he was contacted by Dazai regarding the presence of Master Carlyle at the agency office, however Kunikida sends his regards and proceeds to bound the train. He then witnesses someone giving a briefcase to a young girl and remembers Tanizaki's statement about a bomber giving explosive sachels. He runs towards the young girl and steals the briefcase, upon which opening, contains a bomb. Kunikida immediately runs outside and throws the briefcase mid-air. He immediately contacts the relief and forensics team for the matter. On the other hand, the young girl named Aya urges Kunikida to find the criminal.

Battle
The two proceed to investigate the underground subway and Kunikida discovers motion-sensing explosives along the trail racks. He then notices Aya's presense gone and upon turning back, he sees Aya strapped with eplosives. He was then ordered by a hooded guy to drop his gun and proceeds to knock him out.

Kunikida is seen tied up in to a post. The hooded man reveals himself as Shōsaku Katsura, a man Kunikida arrested two years ago due to his plan on bombing his school. Katsura proceeds to hit Kunikida numerous times expressing his anger and reveals the time remaining until the bomb explodes when a train passes and his ideals and agency pride will disappear. Kunikida tells him that he is right and tells him to open the notebook on page 89. Upon opening the page, a stun grenade materializes causing a loud noise and Kunikida eventually escapes froom the tie and restrains Katsura.

He rushes over to Aya but she insists on stopping the time on the explosives placed at the train rail, but Kunikida fails to do so. Katsura reveals that the signal to diarm the bomb on the rail tracks are the same with what Aya have, and forcing to remove it will cause an explosion. With the dilemma to save either Aya or the passengers at the train, he disarms the bomb on the rail tracks and hugs Aya telling her he will be with her at the end. The explosives on Aya finally explodes.

After the smoke dispers, Katsura see Kunikida and Aya both standing and alive - being them healed by Akiko Yosano's ability after their fatal injuries.

Aftermath
Katsura acknowledges Kunikida's ideals and gives up. He then surrenders and is arrested by the police.

Manga and Anime Differences

 * In the manga, the explosives strapped in Aya are near her neck. In the anime, it was strapped on her torso.