Complex sentence: Shuya and Naoki's recollections revealed that Shuya said he had upgraded the anti-mugger wallet, and decided to try it out on someone, and roped Naoki in to help with his plan.
Split into simpler sentences: Shuya and Naoki's recollections revealed that Shuya said he had upgraded the anti-mugger wallet. He decided to try it out on someone and roped Naoki in to help with his plan.