In the past year, there were five arrests in Fukuoka involving grenades. Police reported that some residents have discovered hand grenades. One was even seized from a car, noted Japan Today.
It's unclear whether these are factory-made hand grenades or homemade ones.
Those looking to earn the reward need to provide information that leads to either the arrest of those possessing hand grenades or simply the seizure of the grenades. Just the pins doesn't count!
Nice work if you can get it (and not be blown to bits).
Fukuoka offers cash rewards for hand grenades [Japan Today]