Because the Remake's out in English officially this June 27th on PS4 and Switch: https://www.rpgsite.net/news/15653-tsukihime-a-piece-blue-glass-moon-release-date-set-for-june-27

Thankfully, it's never been easier to read Tsukihime and thus achieve culture in English. The game is basically abandonware outside Japan so there's no piracy ick (if that's even a real problem, idk), and there are several good ways to read it.

You can check out ways to download and patch the original game for local play here: https://www.readtsukihi.me/

Or even try out a full fan-made web browser port here: https://tsukiweb.holofield.fr/
Assuming it works (many have said it's fine but I haven't tried yet so I'm not 100% sure), browser port is kind of amazing because it even includes a soundtrack toggle for all three versions of the Tsukihime OST (I prefer the Tsuki-Bako remix myself).

There are 5 routes in OG Tsukihime (the remake coming out in June actually only has the first two "Near Side" routes with the other 3 and any extras coming in further installments that will hopefully take less than 12 years to develop), but they're all easily accessed with some simple guides. I recommend Skeith's on Fuwanovel: https://forums.fuwanovel.net/topic/983-tsukihime/