This series provides examples of:
- Action Girl: Kelly who can take out multiple armed soldiers on her own, armed with only a handgun.
- Aloof Big Brother: Souma Ken did not contact his younger brother for three years, is cold when they are reunited, and leaves his brother behind after turning him into a Half-Human Hybrid (that move can be interpreted in multiple ways).
- Always Identical Twins: Souma Ken and Shin.
- An Arm and a Leg: Several characters nearly get this, but are turned into human-plant hybrids, preventing this.
- An Offer You Can't Refuse: This is why Shin ends up working for the military.
- Anyone Can Die: Several long standing villains get this, as does Souma Shin (subverted in the last case, since he gets better).
- Artificial Limbs: Several characters, including Shin, end up with plant-based prosthetics.
- Attack Drone / Mecha-Mooks / Plant Mooks: The Arethusa are nearly indestructible plant mechas usually controlled by the plant system as a whole.
- Badass and Child Duo: Shin with Dina and her elder brother.
- Big Brother Instinct: Although it is unclear to what extent Ken has this for Shin, Shin clearly feels this way for Dina and her elder brother (who also feels this way about Dina).
- Big Damn Heroes: Shin has a few moments, as does Kelly.
- Blessed with Suck: Becoming a Half-Human Hybrid may make you basically unkillable, but if you get injured too much, the plant will continuously grow and take over your body.
- Bodyguard Crush: While she isn’t his body exactly, Kelly often takes on this role, so Kelly and Ken’s implied relationship is this.
- Body Horror: Slowly transforming into an Arethusa definitely qualifies.
- Bullet Catch: Becoming an Arethusa makes this possible.
- Casual Danger Dialogue: Shin pulls this from time to time.
- The Corruption: The more the plants inside of him grow, the more Shin becomes taken over by them.
- Damsel in Distress / Damsel out of Distress: Dina goes both ways.
- Determinator: Shin and Ken both.
- Dying Momentof Awesome: When Shin is about to be completely taken over by the plants inside of him, he smiles and says:"If I had something clever to say right now, it’d be pretty badass. See ya."
- Fighting from the Inside: An unusual variation occurs when Shin tries to shave off the excess plant material from his face, his plant arm tries to stop him.
- Gaia's Vengeance: In the setting, this has been occurring on a global scale.
- Half-Human Hybrid: Shin becomes a half-human half-plant hybrid. Serveral other characters also become this, including two villains, Ken, and Kelly.
- Lab Coat Of Science And Medicine: Ken always sports one, as do other characters associated with either field.
- Mad Scientist: Ken shows shades of this.
- Morality Kitchen Sink: Many of the good characters have either ulterior motives or questionable methods, but some of them are simply good; there are also villains who are mostly good and ones who are out right evil.
- Off with His Head!: This is what Shin is threatened with, later this ultimately gives him a second chance at life.
- One-Man Army: Shin becomes one, but he was really tough to begin with.
- Power Degeneration: Becoming an Arethusa also means loosing yourself, effectively killing you.
- Power Incontinence: Half-Human Hybrids have this, since the plant-matter slowly takes over the host body.
- Precocious Crush: Dina clearly has one for Shin (whether he eventually reciprocates is left open to interpretation).
- The Professor: Souma Ken.
- Rescue Romance: This is hinted at between both Shin and Dina and Kelly and Ken.
- Shirtless Scene: There are several times where Shin is being examined an thus is not wearing a shirt, this is an instance of Body Horror usually.
- Shout-Out: To Ancient Greek mythology. The plant-mechas are named after Arethusa, one of the Hesperides, who was connections to plant-life in all versions of her myth.
- The Speechless: After being shot in the head, Kelly’s speech centre was damaged, so she cannot communicate at all.
- The ending has her intelligible to areopaths.
- Waif Prophet: Dina and other areopaths know a lot more about the present global circumstances than other characters.
- Weapon Wields You: Becoming a half-plant hybrid, means slowly becoming an Arethusa and loosing yourself.
- Why Am I Ticking?: Shin, on multiple accounts.
