Eshii is a level 3 Akuma, with power over gravity.
Eshii's origins are not known, however, in order to become a level 3 Akuma, the Soul of a deceased person must be trapped inside an Akuma body via the Earl of Millennium, rather than resting in peace. This brings about horrible despair for the soul and eventually that despair becomes great enough to descend to a deeper level of evil, a level 2. To become a level 3, the despair must be greater still and it seems to be relatively rare that even an Akuma reaches such a level as most of the Exorcists that faced Eshii had not seen a level 3 before.
Due to Eshii's short time in the story, there was no noteworthy character development for him.
Eshii has the typical appearance of a Level 3 Akuma. A tall humanoid skeleton-like being. He has what appears to be skeletal wings as well as fairly long red hair.
Eshii was very personable for an Akuma which normally are simple if not mindless. Eshii was fully cognitive and had his own unique personality. For unknown reasons, Eshii liked the catchphrase, "Title" before performing an attack.
Eshii served the Noah Family but had no known relationships of note.
After Lenalee had come back from Suman Dark the Fallen One alone and had failed to locate Allen even with Lavi's assistance, the Exorcist crew in route to Edo were glum as they believed Allen to be dead. But they had choice but to proceed with their mission to find Cross Marian, who they believed to be in Edo. But they were to have one final obstacle before reaching the shores of Japan. That was Eishii, a level 3 Akuma, and the first that most of the Exorcists had encountered.
Eshii began attacking the ship with his gravity powers from the air high above. Not only was it difficult to attack him, but his power was so great that all the Exorcists lives and the Crew were at risk. Knowing this, Lenalee Lee, the only Exorcist present that could fly, decided to take the fight away from the ship and face Eshii alone. Lenalee fought to the best of her ability but Eshii dominated. She decided to change strategy, by diving into the ocean and dashing up behind him to catch him off guard. As it was nighttime, it was easy to do. However Eshii quickly adapted and caught Lenalee when she tried to surprise him again and pummeled her. Lenalee still had some fight in her but as she stood on the water as her Dark Boot Innocence allowed her to do, the mechanism started failing and she almost fell through the water's surface. Both Eshii and Lenalee realized that she was low on energy and knew that she could not continue like this.
In a last ditch effort, Lenalee soared high into the sky and channeled the entirety of her remaining Innocence energy into her Dark Boots and shot down towards Eshii at terrifying speed. This was the Falling Shackles Technique. Eshii took the attack head on, attempting to block, but very quickly his defense was shattered. Eshii remarked that it was like the weight of a Meteor falling on him, then was engulfed by the force. Wehn everything was clear, Eshii was no more.
Eshii was physically stronger than Lenalee Lee to the point where he could catch her kicks bare-handed despite them being strong enough to explode Level 1 Akuma.
Eshii was quite durable. None of Lenalee Lee's attacks inflicted noteable damage upon Eshii until she resorted to the Falling Shackles technique that exerted the force of 40,000 Metric Tons. Although able to hold it back briefly, Eshii could not withstand that level of attack.
hains that latch on and weigh down the target. According to Lenalee, they could not be taken off and could only be removed upon Eshii's death.