"AI no Idenshi - Episode 4" is a complex narrative that unfolds across four different cases, each involving distinct characters and their interactions with AI technology.

The episode begins with Dr. Sudo conducting a self-examination. His assistant Risa observes him and expresses a desire to see him in various emotional states. Risa's friend introduces her to a software called Fantasy Generator, which uses AI learning to create stories about people. Despite the humorous and sometimes absurd scenarios it generates, Risa realizes she wants to see Dr. Sudo as he truly is, not in fabricated situations.

The second case involves high school student Nozaki Daisuke, who uses an AI modification to make a game character, Nana, resemble his classmate Suzuki Nao. Despite the initial thrill, Nozaki struggles to distinguish between the virtual and real Nao, leading to an awkward confession and subsequent rejection.

In the third case, Toda Hide, a man struggling with infidelity, seeks help from Dr. Sudo. Dr. Sudo implants a "clarity switch" in Hide's brain to suppress his desires. While this helps Hide remain faithful, it also drains the passion from his relationship, causing his girlfriend to fall for someone else.

The episode concludes with Dr. Sudo planning further tests on a blood sample. Throughout the episode, the characters grapple with the blurring boundaries between reality and the virtual world, exploring the impact of AI on human relationships and self-perception.