what I understand is that if you get the bug disease and you do drugs, you'll "Bug Out" and become a monster.
The biorg-bug disease seems to give the victim some inhuman superpowers along with freaky transformation, hard to control at first. Also those who get the disease will have to do some registration (perhaps regulated by the government with some special laws, to keep those with potential dangerous power in check) and attend training to gain control of their abilities (as the tiny old man called Madola-sensei suggested). Those who are responsible for the training, obviously, are those who have mastered their abilities themselves and are trusted by the authority. That green-haired ponytail bossy Naruto fangirl, Kiwako, could be one of the trainers, though it is unclear whether she got her power from the disease or from technology.
Getting superpower from bugs reminds me of Spider-man, but since superpowers in Biorg are so common, the authority here does a better job in regulating superpowers.
From what we are shown, apparently Fujii contracted the disease when he dived into the river to take back his smartphone and got infected by the fishy monster passing-by. His hands got swollen and generated 'killing-intent'. Then it left him with two heart-shaped holes that apparently have the power of sucking things into another dimension (kind of like Doraemon's pocket).
The effect of drug on the victim is for now unclear. Apparently it stimulates the power for a short time but also leaves dangerous side-effect and can send the drug-user to hospital after getting them high, which is why it is banned by the authority. Chieri herself was also unclear about the effect of the drug, saying "it didn't work'. The reason why she sneaked out of Kiwako's sight and tried the drug probably stemmed from her insecurity, inferiority complex and obsession with being cute. She probably heard rumor about it from the Internet, downloaded it and tried, thinking it can solve her problem somehow.
Aside from Matsukage Chieri, there seems to be another person in the school who recently got the disease before the main character and Kiwako was training with that person (as referred to by Chieri herself as 'the other'). That person is possibly Enomoto Fumiho - Fujii's love interest. That would explain why he said Enomoto also loved empty bug-holes and asked Kiwako to help him to connect with Enomoto.
Kiwako's reactions to Fujii's asking for her help suggest that she is also secretly 'in love' with Fujii and mocks him to hide her feelings. Since she outwardly treats him like a kid and he views her as an older sister (although they are in the same class), it is hard to confess indeed.
Perhaps we will get to see them training together soon, and get a better explanation of their powers. The class representative with wavy hair and the Eiji Niizuma-lookalike will be involved somehow. Not sure who the trinity is among the five characters shown in the cover.
Also, technology is really advanced in this series, as your phone can "bond" with you, you can download drugs, and explain yourself by showing a code to a police officer.
The worst thing is Naruto is still running by the time they get those technology.