Nimetazepam is structurally related to flunitrazepam (the only difference being flunitrazepam's fluorine group on the phenyl ring). Flunitrazepam ("rohypnol") was considered an extremely abuseable benzo, especially since its effects tended to lean on the sedative-hypnotic side. Concerns of widespread abuse have since led to nimetazepam being withdrawn from the market, or atleast tightly regulated, in a number of East Asian countries.
Speaking of
regulated, should you attempt to acquire it (which I would advise against, it being an extremely addictive benzo), do make sure that it isn't "scheduled" in your location. This isn't some exotic NPS/RC benzo that goes straight from "unscheduled" to "banned". Since it is (or atleast used to be) a common pharma drug in some parts of the world, this has led to it being a Controlled Substance in other parts of the world, even if it was never sold commercially there. Germany, for example, lists Nimetazepam as an "Anlage III" substance, meaning it can
technically be legally prescribed under special circumstances, and
importing it illegally would likely incur similar legal consequences as trying to acquire other "Anlage III" substances, such as fentanyl or dextroamphetamine.
As for "Happy 5", this is apparently simply the street name for nimetazepam, named after the Japanese 5mg "Erimin 5" tablets. Since those have been discontinued by the manufacturer, it is likely that any "Erimin 5's" you find on the street are simply counterfeits, many of which probably contain some RC benzo, as opposed to actual nimetazepam... basically the same situation as with xanax bars in the West.
