"I know I promised I'd be home soon... and I'm sorry to break that promise... But, I want you to know... Daddy was the happiest man on earth when he was with you. I love you, Yukari. Please take care of yourself."
- Aegis: The First Mission
- Persona 3 / FES / Portable: Major Character
- Persona 3 (Manga): Major Character
Eiichiro's personality cannot really be inferred due to his short appearance but it is obvious that, at the very least, Eiichiro cared for his family deeply especially his daughter, Yukari. Ikutsuki notes multiple times that he was a great man.
Aegis: The First Mission
Eiichiro Takeba appears as a scientist who helps Aigis.
Prior to the events of Persona 3, Eiichiro Takeba was a brilliant scientist whose talents immediately gained recognition, leading an invitation to join the Kirijo Group's research on Shadows. Before leaving his daughter and his wife behind, Eiichiro Takeba wrote a letter to his daughter, which he intended her to receive ten years later.
While researching the Shadows, the scientists learned about the prophecy of the Fall. Many of the scientists willingly embraced the belief and shifted their research towards bringing about the Fall themselves. However, Eiichiro Takeba objected to the belief of Death as a deliverance and during the final stages of the experiment to create Death, he interrupted the process and forcefully separated the harbinger of the Fall, Death, into thirteen parts. Before Death was separated, however, he left a video recorded warning that would not be seen for another ten years.
Death's separation, however, caused the Shadows to go berserk and created a massive explosion, destroying the facility and the original Gekkoukan High School completely. The results of the explosion led to the existence of the Dark Hour and the summoning of Tartarus, where Nyx was to descend to bring about the Fall. Unfortunately, Eiichiro, like most of the scientists in the facility, died in the aftermath of the explosion and he was used as a scapegoat by the public in order to cover up the truth of the experiment. The hostility towards the Takeba family caused them to move several times, though Yukari never stopped believing that her father was innocent.
After Eiichiro's death, his devastated wife began throwing herself towards random men, an act which disgusted her daughter, Yukari Takeba and led to the two becoming increasingly distant towards each other. When Yukari enrolled at Gekkoukan High School, she finally received the letter her father wrote 10 years ago. Realizing her father's wishes and his love for her, Yukari decided to join SEES, and hopefully learn the truth about the events that caused her father's death.
Shuji Ikutsuki finally recovered the recording and showed it to the members of SEES after having invited them to Yakushima for vacation. In the recording, Eiichiro appeared to take the full blame for the experiment's disastrous results and begged whoever saw it to defeat the thirteen shadows to forever banish the Dark Hour. Yukari, who up until that point had been angry over what she saw as cleaning up the Kirijo group's mistakes, was devastated by the revelation and her faith in her father was shattered.
However, after the defeat of the final Shadow, the Dark Hour did not disappear and Ikutsuki revealed that he had been manipulating SEES the entire time in order to bring about the Fall, including altering Eiichiro's final words to trick SEES into thinking they were actually saving the world and not, as it turned out, allowing the Shadows to reunite into Death. After Ikutsuki's death, Fuuka Yamagishi recovered the original recording and Yukari finally learned that her belief in her father had not been in vain, as the original video revealed that his intents had been to save the world from the Fall and the video had been intended as a warning to stop anyone from letting Death reunite. At the end of the recording, he left a message for Yukari to tell her how much he loved her and an apology for all the time he spent away from her. The truth of her father's feelings strengthens Yukari's resolve, which evolves her Persona into Isis.