Best firefly festival in Honshu

Hi All,

I'm planning for my summer trip. Is this possible that you recommend me a firefly festival in Honshu? I would prefer somewhere with big number of fireflies yet friendly with those who can only go with public transportation, and festival time around 20 Jun.
As I check by myself, Tatsuno Hotaru Festival (辰野ほたる祭り) in Nagano seems to be the biggest one; however it ends on 16 Jun 2024. I can still make it but it's a bit hectic for me since I arrive in Tokyo in late 15 Jun.
One more question - will the number of fireflies do affect the viewing experience? Or I'll feel good anyway :)

Thanks in advance for your kind comments.

I haven't been there yet, but I'd like to go to the garden of Chinzan-so.
This hotel is also famous for its fireflies.
But you need to use restaurants and so on.
https://hotel-chinzanso-tokyo.jp/column/firefly/
https://hotel-chinzanso-tokyo.com/garden/topic/firefly-viewing-at-hote...
https://www.hotel-chinzanso-tokyo.com/garden/seasons_summer/?doing_wp_...
I think you can also see it at this Japanese restaurant that has decided to close next year.
https://kuruma-ya.co.jp/shop/showa
https://www.instagram.com/p/BlIcp0BlAV8/?hl=ja
In addition to these two places, this article also introduces "Nagusa Firefly Festival" in Tochigi and Tsukiyono in Gunma.
https://precious.jp/articles/-/5950
Nagusa
https://www.ashikaga-kankou.jp/event/nagusa_hotaru
Tsukiyono
https://www.town.minakami.gunma.jp/life/09sumai/kankyou/2016-1013-1155...
https://www.enjoy-minakami.jp/hotaru.php
I have been to Tsukiyono on the way to Sarugakyo Onsen.

Please also refer to this.
https://weathernews.jp/hotaru/