There you have it! The Grinns Tale Music is created by Wataru Hokoyama.
(Before we go through his bio, let's listen to his creation <3)
Wataru Hokoyama (鋒山 亘 Hokoyama Wataru, Born August 24, 1974 in Aizu, Fukushima, Japan) is a Japanese composer based in Hollywood,California, USA. He has attended the Interlochen Arts Academy, the Cleveland Institute of Music, and the University of Southern California Thornton School of Music. His recent works include the original score for "Bean Cake," winner, 2001 Cannes Film Festival Palme d'Or, short film category;"Ocha Cups for Christmas," winner, 2002 Emmy Award for Best Student Short Drama and 2003 Cannes Film Festival Official Invitation Showing; and"One," winner, 2003 Sundance Film Festival Online Audience Award, short film category. Recent orchestration projects include "Dungeons and Dragon," and additional work on the Joss Whedon penned "Mrs," from Buffy the Vampire Slayer episode 7ABB05 "Selfless."
In 2008, Wataru composed the original soundtrack for the video game Afrika . The soundtrack was released in Japan. The music was awarded Best Original Video Game Score by The Hollywood Music Awards 2008. Movie Music UK has the only review of the soundtrack and gave it 4.5/5.0, saying "Hokoyama has left a strong impression with the wonderful music he has composed. This is a soundtrack you cannot pass up."
In 2009, Wataru provided orchestral compositions for Resident Evil 5 in collaboration with lead composer Kota Suzuki. This was his second video game composition.