A record 4,321 individuals were involved in cannabis cases in Japan last year, up 743 from the previous year for the sixth consecutive year of increase, with abuse of the drug by young people showing a marked rise, police said Thursday.

The number of those aged 14 to 19 involved in cannabis cases probed by the police jumped 4.4-fold from 2.0 per 100,000 people in that age group in 2015 to 8.7, according to the National Police Agency data.

The number of people in their 20s per 100,000 more than doubled to 15.5 from 6.9 in the same period, according to the agency.

Overall, 4.3 individuals per 100,000 were involved in cannabis offenses last year, more than doubling from 2.1 in 2015.

Of the 4,321 people, 609 were aged between 14 and 19, up 180, or up about 42 percent from the previous year, and 1,950 among those in their 20s, up 429, or about 28 percent.

The agency warned that young people are less aware of the risks associated with cannabis use compared with hard drugs such as methamphetamine and tend to begin taking cannabis out of curiosity.

"It is necessary to correctly inform them about the harmful effects (of cannabis) such as a severe influence on cognitive functions and higher risk of developing mental symptoms," it said.

Among the young cannabis offenders in 2019, 109 were high school students and six were junior high school students, with the youngest being a 14-year-old male student.

In other age groups, 7.3 people per 100,000 were involved in cannabis cases among those in their 30s, up from 4.3 in 2015, 2.7 for those in their 40s, up from 1.4, and 0.4 for those in their 50s and older, up from 0.2.

The agency also surveyed awareness of the risks of using the drug among 631 offenders of all ages and found only 15.4 percent think it is dangerous. Meanwhile, 78.6 percent of them said methamphetamine poses a danger.

Meanwhile, the number of people involved in drug offenses in general in 2019 dropped 498 from the previous year to 13,364, with the figure remaining almost flat in recent years.

Among all drug offenders in Japan, 8,584 were involved with methamphetamine or amphetamines, known as "stimulant drugs" in Japan, down 1,284 from the previous year, followed by those involved with cannabis, and 205 cocaine.

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The volume of confiscated stimulants more than doubled from the previous year to a record 2,293.1 kilograms last year.

There were a series of large-scale raids including the seizure of about 1,000 kg of stimulants in waters off Shizuoka Prefecture, central Japan, in June and some 590 kg in the sea off Kumamoto Prefecture, southwestern Japan, in December.

The volume of confiscated cannabis in various forms also increased from the previous year, including 350.2 kg of marijuana and 12.8 kg of hashish. Seizure of synthetic drugs including MDMA also surged six-fold to 73,935 pills.

Stimulants were sold on the street for around 64,000 yen ($600) per gram, while marijuana sold for around 6,000 yen.