It's a cultural thing

Wow.  Japanese litigation sounds as ambulance chasing as anything you see in America:

Twenty-eight girls and women suffering what they say are side effects from a cervical cancer vaccine that was recommended by the government demanded compensation from the state and drugmakers Monday as their trial opened at the Tokyo District Court.
The plaintiffs, ranging in age from 15 to 22, said they have experienced a wide range of health problems, including pain all over their bodies and impaired mobility, after receiving the human papillomavirus (HPV) vaccines between 2010 and 2013.
Each is demanding ¥15 million in damages.
Erina Sonoda, a 20-year-old college student, said she started to suffer strong menstrual pain after receiving the second of three recommended shots of the Cervarix vaccine, and the pain spread to other parts of her body after the third vaccination.
Due to agonizing pain, Sonoda said she has difficulty walking without a cane and often must use a wheelchair.

Have a look at the PR photo at the link, too.

I suspect that there is a strong cultural element to this.   The Japanese, for reasons not entirely clear, are extremely cautious about anything "unnatural" to do with women's reproductive health.  The prime evidence for this:  the contraceptive pill was only legalised in 1999, and its use is still startling small:

In 1999, Japan became the last industrialized country to legalize oral contraceptives (OCs). Have contraceptive use patterns changed as a result?

An analysis of national survey data indicates that, as of 2014, prevalence of condom use and OC use was 83% and 3%, respectively, among all Japanese women aged 16 to 49. According to the UN, among married women in 2011, the proportions using OCs were 1% (Japan), 16% (U.S.), 21% (Canada), 28% (U.K.), 37% (Germany), and 41% (France). Prevalence of OC use in Japan did not significantly change following government approval.

So with this background, hysterical reaction to an injection that affects something to do with female reproduction was probably foreseeable.