We know now the developer behind Yoshi and the Mysterious Book.

To nobody’s surprise, the developer is Good-Feel. Good-Feel also made Yoshi’s Crafted World for the Switch and Yoshi’s Woolly World on the Wii U. Their last game prior to this was Princess Peach Showtime for the Switch.
Good-Feel is a completely independent studio founded by former Konami devs Etsunobu Ebisu and Shigeharu Umezaki. They’ve made games exclusively for Nintendo for the past two decades, seemingly because they’ve just been so successful with them.
Good-Feel used Unreal to make Yoshi’s Crafted World. So this revelation seems to confirm the recent rumor that Yoshi and the Mysterious Book was also made using Unreal.
Video Games Chronicle, who revealed Good-Feel’s indentity in their review, concluded that Yoshi and the Mysterious Book is a brilliant title. This conclusion is borne by the game’s MetaCritic as well.
Suffice to say Nintendo is still very much on a roll making games, regardless of how the market is doing.
