Some report says 56.4% of the family of suicides has suffered from prejudice. I think it is an evidence that ctb is thought to be a taboo in Japan.
http://www.lifelink.or.jp/hp/Library/whitepaper2_4.pdf
(P.12 written in Japanese, Jisatsu Jittai Hakusyo, Suicide fact-finding white paper)
Most Japanese born after WW2 think Seppuku is a cultural event only permitted to less than 10% people called Samurai mainly during Edo-era, which ended about 150 years ago.
They, including me, do not think the ethics or philosophy behind Seppuku affect their integrity or personality, including their judgment for or against ctb.
Some (teens to 20's generally) tend to seek, and as Noiseless mentioned practically easily have, a mate or group for ctb through twitter or other social media just like Partners Megathread here.