One of the earliest projects that included features resembling the DSi was the Game Boy Camera. The idea behind the camera was “take, look, play.” The first prototype was made by Mr. Kuwahara around 1996, but he was told by his department that it was a trivial idea. He was about to give up, but then he heard there was another group working on a similar project. This other project was being developed by Hip Tanaka, known for his musical work in early Nintendo games. They showed each other theirprototypes, combining Kuwahara’s hardware and Tanaka’s software to form a cohesive product. They then showed their combined prototype to then-Nintendo President Hiroshi Yamauchi, who immediately decided to bring it to market. Mr. Kuwahara detailed how he spent nights and weekends working on the software, designing the FPGA prototype circuit and wiring it by hand. He called his work “yakisoba wiring", or "spaghetti wiring".

In the mid-2000s, he and his co-workers played a lot of Diablo and Diablo 2 in the company lab “trying to come up with product ideas.” Though his boss played too, Mr. Kuwahara said, “I do not in any way encourage you to follow in these footsteps.” Eventually, he came up with an idea that would eventually become the GBA Wireless Adapter. Mr. Kuwahara created the first prototype using GBA cables and a wireless adapter from a cell phone. This prototype was crude, but functional. He didn’t know about CRC (a computer error- checking mechanism), so messages were often corrupted. He eventually received a budget to develop the project further. The development team initially planned to use Bluetooth, but they ran into development problems and opted to design their own wireless system instead.

Shigeru Miyamoto saw the project, thought it was interesting, and wanted to make the wireless adapter work with Four Swords Adventures, though this idea never came to fruition. The project was close to being scrapped, but Satoru Iwata closed a deal with GameFreak to bundle the adapter with Pokemon FireRed/LeafGreen. As a result, about 10 million adapters sold worldwide. Nintendo had more plans for the adapter, but its late arrival and the success of the Nintendo DS ultimately precluded more widespread uses. For instance, download play was implemented in the adapter but never used. As a result, this functionality was kept a secret.

As a result of his work on the GBA wireless adapter, Mr. Kuwahara became the Wireless Lead on the development of the Nintendo DS. Over 100 engineers were involved in this project, but his team was one of the last to merge due to late GBA development work. At Nintendo at the time there was no feeling that the Internet would play a role in Nintendo games, but thankfully that changed. Mr. Kuwahara was proud that the developers were able to provide a DS wireless mode equal in experience to playing with cables and wireless download play. He was also proud that he came up with the name "Download Play". Another earlier idea of his, "Tag Mode", was used in Nintendogs by notifying players when other players had the same game near them.

Mr. Kuwahara showed off a photo of a canceled Game Boy. Originally set to be released around the time of the Atlanta Olympic Games, the system was known as Project Atlantis. It had a color LCD, powerful ARM processor, and SNES-style buttons, but it was huge and its graphics engine was not very efficient on ARM.

Mr. Kuwahara also showed off a touch panel he originally developed for the Game Boy Color. At the time it was not well received, but after the GBA SP came out he was asked to demo it. Miyamoto liked it, but it was ultimately not chosen to be brought to market. Eventually, the touch screen did show up in the DS. While its addition was not his decision, he would like to think that his work influenced its inclusion.