Border organizes Side Effects into four types:
S - Extrasensory Perception (超感覚 Chō Kankaku)
A - Superhuman Ability (超技能 Chō Ginō)
B - Special Anatomy (特殊体質 Tokushū Taishitsu)
C - Enhanced Senses (強化五感 Kyōka Gokan)
Side Effect Holders
- Yūichi Jin: Seeing a little of the future of those before him.
- Yūma Kuga and Yūgo Kuga: Seeing through the lies of others.
- Chika Amatori: Sensing approaching enemies and hiding her trion signature.
- Yōtarō Rindō: Communicating with animals.
- Shirō Kikuchihara: Enhanced hearing (強化聴覚 Kyōka Chōkaku)
- Kō Murakami: Enhanced stabilization and consolidation of memory during sleep (強化睡眠記憶 Kyōka Suimin Kioku)
- Masato Kageura: Receiving emotion aimed at him from other people (感情受信体質 Kanjou Jushin Taishitsu)
- Tsukihiko Amō: Viewing others' fighting ability as colors.
- Yomi: Perfect Parallel Processing (完全並列同時思考 Kanzen Heiretsu Dōji Shikō), which allows him to multi-task at maximum efficiency.
- A recurring theme in the series sees Side Effects contributing to their possessor's misery:
- Chika's Side Effects allowed her to escape capture at the hands of Trion Warriors for years, and are thus indirectly responsible for her feelings of guilt after her friend was abducted;
- Following his father's death, Yūma's Side Effect allowed him to see through the empty platitudes and attempts at manipulation of the people who surrounded him, some of whom would have preferred his father to survive rather than him.
- Jin's ability to see the future comes with great responsibility, as he may be forced with the choice of letting someone be injured or even die to prevent a worse outcome.
- Kikuchihara was mocked for the supposed inutility of his Side Effect, with it causing him to overhear himself being mocked.
- Murakami lost friends due to his Side Effect allowing him to surpass them in their favorite activities in a short time, causing the group to disintegrate.
- Kageura is not only privy to others' negative feelings towards him, but the prickling sensation provoked by his Side Effect is all the more unpleasant if the emotion directed at him is a negative one.