Eren is Shingeki no Kyojin's protagonist. His childhood friend, Mikasa, notes on numerous occasions that he acts on impulse without thinking things through, and she often pulls/carries/throws him when he starts fighting with others to protect him from himself. Along with Mikasa, he tends to spend his free time with their mutual friend, Armin. His father is a doctor (whom is well respected by Hannes and potentially many more) whilst his mother is a housewife.

The female protagonist. Makise Kurisu is a research member in Victor Qondria University's Brain Research Program. Her age group matches that of third-year high schoolers, but she skipped a grade through America's educational system. She is also famous in America for writing theses papers, part of which is covered in the news. Thanks to skipping a grade in America as a girl, she was envied by people around her, and ended up building a strong personality. She does not want to show weakness to others, so she always has a stern expression. However, she is very curious, and when she builds interest, she pokes into things. Occasionally, she has views that differ from regular opinions, such as, "The experiment data is more important than the subject's privacy." Rintarou often tells her, "Hey, you've got a pretty good sense of being a Mad Scientist," but she is not one to agree to such things personally. She is a tsundere. Rintarou has given her plenty of nicknames, in particular "Christina" (クリスティーナ) and "Assistant" (助手).