So wait...
Who owns the rights to this again? I thought the original company that made it went under?
It's what I'm wondering. From all I can tell, the company went under in the early 2000s when they were working on an English release, and then the state of the original White Day was left in an unknown status for years. But in the last 3-6 years, a company that had formed from the old one's ashes tried to get the rights back to the IP since they wanted to do more with it, and from my understanding they either own the rights to the WhiteDay IP and evidently can remake it, buuuuut they apparently no longer have the rights to the original game, or have just chosen not to enforce the copyright on the original since White Day has grown more popular since the fan translation and such than it was before it. Which might be one of the reasons they're completely remaking it. In the conference, they pointed out the fan translation and various YouTube let's plays of the original game as saying there's a bigger market for White Day and international audiences, and it's easier to release things on PC now than it was 15 years ago, so it seems they're taking the route of just kind of... Leaving the original alone, either because they can't or they're just choosing not too since the original game bombed hard, made the studio close down, and there was no release outside of Korea and some fans took it in their own hands to make it more available to outside audiences. There is a chance they view it being in the public like this more of a positive than a negative thing.
And it looks like the remake they're working on right now has a number of additions to it. There's a number of new mechanics, including being able to peek under bathroom stalls, open doors a crack to peek through, have to manually input keys... We've seen the first puzzle has been completely redone and they changed the alarm in what many considered an annoying sound at the start when you have to turn it off. We see there's new story moments, and there's a high chance of new locations. There's also 21 ghosts in the remake, as opposed to the 8-9 ghost in the original, and in the conference you can briefly see the appearances of 9 of the new ghosts quickly.
The original game had a lot of content cut from it that never ended up in the game. According to an interview, they want this release to completely replace the original White Day; keep what people love about it, and keep all the original scenes in (and they even have all the original audio design, kept the non-photorealistic style of the original, and even went as far as to keep the original dialogue, but actually find the original voice actors and make them record new dialogue), but also say they want this to be a remake that fixes the issues the original game had, and a director's cut, where they're adding in a lot of the scrapped things back into the game and adding new stuff they want to put in 15 years later.
---
So the gist of it either they don't own the rights to the original game, or don't mind the original game being available publicly online, they even point to the success of it being publicly online to help grow its recognition and prove there's audiences for this game in their conference on it. They seem to have re-gotten their copyright on WhiteDay there are a number of people involved in the original game on the remake, including the original director, artist, composer, and lead programmer, and the original voice actors. But they're a new studio now, and it seems they want to remake White Day but make it better in every way possible. They also seem to have long-term plans for the IP, they showed a chart for the WhiteDay IP at the conference, and showed they wanted to do a few more releases related to WhiteDay after the remake leading all the way to 2030.