I've been looking for these models for a very, very long time, but it just seems like those models are no longer available. The only way to get them would be if someone who had them downloaded still has them saved. But I don't want to break the rules of the person who made these models throught if they said those models cannot be redistributed.

But here is barely no information about these models, all we know is that those models were made by person who goes by "Zero", and that here is a few footages of these models.

Know footages:

https://www.deviantart.com/mikelaruku/art/Mmd-Windows-8-Madobe-Yuu-And-AI-339259477 - This is what I uploaded in this post

https://www.nicovideo.jp/watch/sm19406810 - A video featuring those models, HUGE possibility this was made by the person who made these models, as in the description the person doesn't not credit anyone for those models and says "improved version of something I made", it was machine-translated, but the context can be understood. The account that posted the video is probably deleted. Meaning that if the video was uploaded by the person who created those models, then here's possibility that those models are not available for download.

The video said it's "polished" or "improvement" version of these models, meaning that here probably could exist another video or something related to these models and possibly linking to the download of these models.

https://seiga.nicovideo.jp/seiga/im2829182 another link featuring Ai's model from this models. I can't prove if the link exist or not because I get a message that the service is not avaiable in my country, but this link has been archived at web.archive.org just without the image, but the image if you search deeply enough can be found on Google in some quality.

The tags also said "かなで♪" which is the name of the uploader, it made me to think that those models were either made by かなで♪ and missunderstood happened, and wrong person is credited for the models and Zero just did some footage with those models but didn't created them but possibly shared the link so the person who made this image thought Zero created those models because they shared the link, or Zero also goes by かなで♪, or the person who uploaded the Seiga nico upload just uses their name as tag and didn't created those models, but if they didn't created those models, then why they didn't credited the person who made those models?

Also the web.archive.org page from 2013 about the video says it was uploaded by "こむ さん" but it is not clickable, I wonder if that is just a name for deleted account or something.

So I guess with all that I've found, the only way to get those models would be to contact the people who made those footages if they don't have those models or don't know where they downloaded them or if they doesn't have link to download them. Because those models could still exist for download but with some name like "Windows 8 mascots" instead of "Madobe Yuu and Ai".