Attendance by women at an annual self-defense seminar in Uruma, Okinawa Prefecture, increased fivefold this year amid heightened concern following the recent murder of a local woman allegedly at the hands of a U.S. base worker.

Hosted by Uruma Police Station, as many as 150 women took part in Monday’s seminar, which is traditionally held at the beginning of summer, a time when sex crimes peak.

The murder of Rina Shimabukuro, 20, late last month prompted many first-timers to show up at this year’s event.

“I could have been the one who was assaulted,” said Yumeka Nagamine, 21, a local office worker, referring to alleged reports that Kenneth Franklin Shinzato, the suspect who is also a former marine, had driven around for several hours looking for a victim.

Shimabukuro was reportedly attacked just before arriving home after a walk.

Nagamine said she had been approached by U.S. soldiers in the past when walking past Kadena Air Base.

“I became stiff and couldn’t move,” she recalled.

During the seminar, Nagamine watched intensely with other participants as police officers demonstrated how to defend against someone trying to grab them by the arm.

“I feel deeply sorry for the victim who passed away. I can’t even start to think what if it were my daughters,” said Mirei Kadena, 36, a mother of two teenage girls.

She attended the seminar out of a sense of urgency to learn what she can do as a parent.

Kadena said she was once approached by a U.S. soldier when she was waiting at a stop light in her car on her way to work.

“I felt a chill,” she said. Since then, she keeps her car windows rolled up.

Still, Kadena said she is aware that Japanese commit crimes as well and that it would not be right to show prejudice against U.S. servicemen.

“But this incident would have never happened if it weren’t for the (U.S.) base,” she said.