Ein

Ein is Hayate's alter ego, who he first debuted as in Dead or Alive 2. During the time Hayate was suffering from amnesia, due the effects of Project Epsilon, he was found by Hitomi and trained the art in the of karate with her, going by the name of "Ein." By entering the second Dead or Alive Tournament, he was able to regain lost his memories. Even after Hayate returns to his normal state, Hitomi still calls him "Ein"; it's unknown if she is unaware of his true self or if this is now just her nickname for him.

Ein is also a secret character for Dead or Alive 3 and Dead or Alive 4; in Dead or Alive 3, he is unlocked by completing all of the character's story modes, then playing as Hayate on Survival Mode, getting at least three wins then entering "EIN" on the scoreboard. He is easily unlocked in Dead or Alive 4 by just completing Hitomi's story.

The name "Ein" likely comes from "eins", the German word for "one" or "first".

History
Before the events of Dead or Alive 2, Hayate was captured by DOATEC and became their subeject for Project Epsilon, created by Victor Donovan. The project was suppose to turn him into a superhuman-like creature, but it failed and Hayate had lost his memories. Later on, Lisa released him; it's unknown if she did this for Hayate's sake or to just go against the company.

Hayate was later found in the of Germany by Hitomi and her father, and they took him in. Since he didn't know his name, they named him "Ein". Alongside Hitomi, he worked in the family's dojo and mastered karate in a short period of time. Wanting to find out who he was and where he came from, "Ein" entered the second Dead or Alive Tournament on a journey of self-discovery.

Dead or Alive 2
Along the way in the tournament, Ein meets up with Ryu Hayabusa and Ayane, who both wonder if he is really Hayate, and Helena Douglas, who talks about the failed Project Espilon, which confused Ein. He finally meets up with Kasumi, Hayate's younger sister, and after fighting her, he remembers who he really is: Hayate, the shinobi of the wind. Hayate then returns to his normal life once more.

Personality
Ein's personality is somewhat similar to Hayate as he seems to be reserve, but quiet. However, Ein is also seems ignorant at times; he would rather get with the fight instead of conversing to find out answers.

Like most fighters in the series, he is skilled and dedicated to his style, with a great understanding of martial arts even though his conscious memory did not return - If he was not, Hitomi would not have sought him out in order to help rebuild her father’s dojo. In his spare time, Ein practices breaking bottles with his hand by slicing the tops of them of in a demonstration of skill and entertainment.

Gameplay
Being the predecessor to Hitomi, Ein is a medium-damage strike character with excellent high-position combos (F, Y or Tsubauchi). He's best played from an aggressive standpoint, where he can position himself close to the enemy. However, a weakness shared between the two is the slight "wind-up" timeframe needed prior to the execution of attacks.

Musical Themes

 * Vigaku - Dead or Alive 2 and Dead or Alive 4

Trivia

 * Ein has tag moves with Hitomi, Ayane, Jann Lee, Kasumi, Ryu, Bass and Zack.