Aika's primary weapon. It fires darts that are used to render victims unconscious. In Agent Aika, the darts were red, in the Aika Prequels, the darts are golden.
These are used in the original Agent Aika series. Although it canonically comes second (timeline-wise), this is the first one we see. The darts that we see are short and red. Like the other two series, we often see the tranquilizer gun fire, but do not see the darts on the unconscious body. These darts do take quick effect, leaving the women unconscious within three seconds of impact.
The target area of these tranquillisers is the buttocks or the neck.
Model 2 is used in Aika R-16 and Aika Zero. It resembles a gun more closely than the Model 1. In Agent Aika, the tranquilizer gun was used exclusively by Aika. In Aika R-16 and Aika Zero, the tranquilizer gun is used by most of the main characters. As we see in all of the Aika series, the darts are usually not visible. We know someone has been hit by a dart when we hear a gun shot, the victim jerks, and falls unconscious. We are unsure of how long the tranquilizer darts work for, In Aika R-16, they were effective for long periods of time, but in Aika Zero, Risako gets shot and is only under for a few hours.
Agent Aika Victims
The tranquilizer gun is not used extensively in Agent Aika, since the preference goes towards the many variants of possible physical KO's. It is however featured quite extensively in Episode 6, Silver Wild Grapevine. In this episode, Aika uses it to knock out first two Black Delmo, one with a well aimed shot to the butt and the other one with a dart in the chest, and then three Blue Delmo. The gun is also used against herself later, but the dart misses with very unfortunate consequences for the shooter, Nina Etsuko.
Aika R-16 Victims
The tranquilizer gun is the preferred KO weapon in Aika R-16. It is featured extensively in both Episodes 1 and 2, and also appears briefly in Episode 3, though it's not used in combat.
Midori is knocked out by Aika with three rounds of the weapon, and so are several girls of the Bikini Squad. Members of the Treasure Hunting Club also meet their fate twice at the hands of the gun (first with the normal variant and second with a more powerful sniper rifle version), and so does Karen, in the last occasion voluntarily shoot by Eri.
Aika Zero Victims
The tranquilizer gun returns again in Aika Zero, though with the addition of a more lethal variant: an SMG.
The two girls knocked out in combat by the regular weapon are Risako Nagisao, by Miyu Shiratori and Misumi, by Risako. Then, the tranquilizer gun is used in several occasions simply to "finish off" already defenseless foes. Neena Hagen uses it this way to take care of the defeated Miyu Shiratori near the end and, even more unnecessary, Karen uses it to hastily put Kana and Rin back to sleep on the metal slab after they regain consciousness.
Then, the one and only knock out by the SMG version is poor Kana Shiraishi, whose defensive shield is destroyed by the strength of the weapon, allowing multiple rounds to get through and end embedded in her body, destroying part of her clothes in the process. The half naked Kana is then left in shock, standing and moaning for some seconds before falling down with a final whimper, her mouth drooling.