There are better, but to get an idea try something like: https://imageresizer.com/image-enlarger. Just needs a sharpening. Source: almost 2 years ago

Now how did I manage to get this printed in 4k? Welp turns out that AI upscaler are WAYYYYY better than I thought. Scarily good in my opinion. As many in this thread have already said, image upscaling was my way to go. So thank you very very much. I used the website https://imageresizer.com/image-enlarger for this image because my original image was too big for waifu2x. I printed it on europosters.de because I... Source: over 2 years ago

In an effort to restore them as much as I could, I used a combination of waifu2x ("Single-Image Super-Resolution for Anime-Style Art using Deep Convolutional Neural Networks"), Clip Studio Paint resize/cleanup tools, and manual cleanup done by hand. Unfortunately, the red text on the title page was a lost cause. If anyone can decipher solid red rectangles please contact me lol. Source: about 1 year ago

Maybe this would help. There's also an app version of it. Source: about 1 year ago

I would recommend putting it through an upscaler beforehand, it seems a bit small. Source: over 1 year ago

Http://waifu2x.udp.jp/index.html found this image upscaler from https://www.reddit.com/r/FireEmblemHeroes/comments/a51f0k/i_turned_yusuke_kozakis_artwork_into_a_high/?st=JPIZKYIB&sh=f12f76fe a while ago, perhaps that would be the closest if IS doesn't release anything. Source: over 1 year ago

You can make it bigger for print by using by using an Japanese AI image enlarging tool. Source: over 1 year ago