Had the same problem, the name of the file is wrong, you can copy:
E3 82 B7 E3 83 A3 E3 83 BC E3 83 AC E3 83 9E E3 83 83 E3 83 95 E3 82 9A
In a hex to text converter where the encoding is UTF-8 or ACII/UTF-8 and it will give you this text:
シャーレマップ
The problem was in the way the last letter is built, in the hex code the letter is built with 2 characters (E3 83 95 E3 82 9A) but in the bad file name it is built as 1 character (E3 83 97).
Edit:
While playing I got stuck on the first minigame, so I suspected that more than 1 file has this problem, so I assumed file corruption and downloaded other versions, I found that Ryzen111 has a good version that gives no error. Then compared the files in the img folder with Total Commander (a file explorer) and it shows that 240 files has this same problem with the name (with other characters too). I assume that the names got changed in the upload or compression process along the way in its travel.
