Warning: SPOILERS for Ready Player One (both the movie and book) are ahead!
Adapting a popular book into a movie or TV show is tricky. In most cases, those involved with the adaptation need to make sure to honor the source material, but then there are also instances where creative liberties need to be taken so that the story flows better in the re-telling. In the case of Ready Player One, while the movie hit most of the main beats from Ernest Cline's novel, it also made a number of alterations, from changing the challenges to obtain James Halliday's keys to giving i-R0k an expanded role. While there are certain Ready Player One elements from the book that we missed seeing in the movie, the Steven Spielberg-helmed project did manage to improve upon the source material in a few ways, and one of the biggest was by making Daito and Shoto more important players in the story (pun slightly intended).
In the Ready Player One novel, Daito, a.k.a. Toshiba Yoshiaki and Sho, a.k.a. Akihide Karatsu, were Gunters like many of the users in the OASIS, and while they weren't on unfriendly terms with Parzival, a.k.a. Wade Watts, they also weren't particularly close with him. In the Ready Player One movie, Datio (played by Win Morisaki) and Sho (played by Phillip Zhao) had a closer relationship with Parzival and Aech, a.k.a. Helen Harris, with the four of them often hanging out with one another in James Halliday's incredible virtual world.
Starting off in the movie, it didn't appear as if Daito and Sho would be particularly important characters, as Wade spent most of his time chatting with either Aech or Art3mis. Even heading into The Shining's Overlook Hotel to look for the Jade Key and its corresponding gate, Daito and Sho don't say much. During the first half of the movie, one wouldn't be faulted for thinking that Daito and Sho wouldn't have much more to do. However the paths they go down compared to their literary counterparts deviate significantly once Nolan Sorrento and IOI learns that Parzival is Wade, and it could be argued that thanks to this change, Wade would not have succeeded in the end if it wasn't for the duo's help.
In the Ready Player One book, after Wade was forced to go into hiding following IOI's unsuccessful attempt to kill him, he learned from Shoto that the Sixers, IOI's goons, went to Japan and threw Daito out of his apartment window, making it look like a suicide. Shoto subsequently went into hiding himself and worked more closely with Wade, Art3mis and Aech to find James Halliday's Easter egg. Shoto was also present at Ogden Morrow's house when Wade arrived there, but because he was already plugged into the OASIS at that point, we never see these two meet in person. Shoto also appears to be a young adult within the book, but we don't learn much else about him, making him a tertiary character at best.
In the movie, on the other hand, both Daito and Sho play a more direct role in the latter half of the story, as they made contact with Aech, met up with her in real life and rescued Wade before he could be captured by IOI following the raid on the Resistance's base. While Daito is around Wade's age, Sho is an 11-year-old kid, making it all the more impressive what he's accomplished within the OASIS. From there, these two directly help in the effort to find James Halliday's Easter egg and thwart IOI's plans. Keeping Daito alive in the movie also pays off during the final conflict, because after sitting out a fair portion of the battle in the OASIS, he dives in and transforms into a life-sized Gundam to significantly weaken Sorrento's Mechagodzilla. Sho also has his own brief moment to shine during that same battle when he slices off i-r0k's arm from afar with a big throwing star. By the time Ready Player One ends, Daito and Sho are both still alive and kicking, and Wade decides to share control of the OASIS with them, Art3mis and Aech.
Had Steven Spielberg's Ready Player One stuck to the book closely, we wouldn't have gotten to know Daito and Sho that well, and the little time we did spend with them would have really only passed along that they were skilled Japanese gamers who nicknamed themselves after swords. Fortunately, they were given a lot more to do in the movie, and it paid off. Rather than just being bit players, they were actively-involved, fleshed-out characters with distinct personalities. Wade, Art3mis and Aech remained the primary protagonists within Ready Player One, but at least now Daito and Sho feel crucial to the story. Ernest Cline is working on a sequel novel to Ready Player One, and if that is someday adapted for a cinematic setting, here's hoping that both Daito and Sho will remain key characters in the movie's version of the events.