Riley Ootori is an employee of Hypnos. She is also the love interest of her manager, Mitsuo Yamaki, who she assists throughout the series, and to whom she also serves as an emotional counterweight to his obsessive, persistent demeanor.
Riley and Tally were perpetually on-hand to announce the frequent Bio-Emergence of various Wild Ones into the real world, including Guilmon, Goblinmon, and Gorillamon. At one point, Riley remarked on how energy fluctuations indicated that they would soon be seeing a level of Bio-Emergence unlike anything they had seen before. Later in that same day, when an energy field was detected in the tunnel beneath the park, Riley questioned Yamaki’s use of the Yuggoth program, suggesting they study it, and noting that unapproved programs were forbidden, but was forced by Yamaki to activate the Yuggoth, which deleted the area.
When a Devidramon Bio-Emerged and made its arrival fairly public, Yamaki charged Riley with inventing a cover story. Later, she announced the Bio-Emergence of IceDevimon, and tried to once again dissuade Yamaki from using the Yuggoth on Musyamon, to no avail, ultimately only temporarily delaying his materialisation. Riley reported the destruction of the Yuggoth deployment when Musyamon returned, then identified his Bio-Emergence point, which Yamaki headed for.
When Riley and Tally picked up an erratic signal that was apparently right under them, Tally spotted Calumon running around the room, and tried to convince Riley of what she had seen, but Riley was having none of it. Later, she assured Tally that whatever the Juggernaut was, it was bad news for someone. When the Juggernaut was then activated, Riley fought through the sound of screaming Digimon while Tally cried out for it to stop. Riley then relayed to Yamaki that the first Deva, Mihiramon, had breached the vortex and was about to enter the real world through the Juggernaut. Mihiramon was subsequently defeated by the Tamers, but his fellow Devas were able to repeatedly use the Juggernaut as a gateway to Earth. Riley detected the Bio-Emergence of Sinduramon, but elected not to alert Yamaki due to his small size. When Sinduramon absorbed the city’s electricity, Riley engaged Hypnos’s back-up power, then called Yamaki in as Sinduramon began to grow.
Riley announced the emergence of Vajramon and Pajiramon, after a Yuggoth deployment failed to stop them, then, when the Tamers destroyed them, tracked Vajramon’s signal as he reconstituted himself.
A little later, Riley was visiting a gym, and was the subject of a bit of gossip from fellow members. The dub has her turning down a date via phone on the pretense that she has to work, then suggesting the following night – but she’s dating Yamaki, so this doesn’t make sense. We don’t actually know she’s his lover at this point, though, so therein lies the reason for the flub. She proceeded to visit the Matsuki bakery while thinking about the fact that only the Tamers were ever successful in fighting Wild Ones, idly noting Takato’s goggles, then went into work, where a friendly conversation with Tally was interrupted by the re-emergence of Vajramon. During the Tamers’ battle with him, Riley analysed the energy increase when Kyubimon Digivolved into Taomon.
When Indramon and Makuramon Bio-Emerged, Riley launched a surveillance virus to tap the communications between the Devas. The Juggernaut was reactivated to deal with Indramon, but it crashed before reaching full power – Indramon departed, and Riley believed he had self-destructed. When Indramon reappeared the following day, Riley recognised his signal.
When Vikaralamon was about to Bio-Emerge, the sheer size of his data almost caused Hypnos to crash. In the ensuing battle between him and the Tamers, the Juggernaut was reactivated and threatened to delete all the Digimon, until Makuramon instigated an explosion that crashed the system and destroyed a substantial portion of the towers. Yamaki refused to leave, and, after a moment of silence between the two of them, instructed Riley to get to safety. The Tamers managed to destroy Vikaralamon, but Hypnos was shut down and Yamaki, Riley and Tally lost their jobs.
As a depressed Yamaki reflected on the situation, Riley made him realise that there had to be something he could do – prompting him to change sides, and help the Tamers out by giving them a comm device before they headed into the Digital World. It was at this point, when we see Riley in casual dress in Yamaki's apartment, that it became evident that Riley and Yamaki are in a relationship (although it is at no point ever stated in dialogue that they are).
Some time later, as Riley was preparing breakfast, Yamaki received an e-mail from the kids – but then, the Juggernaut was reactivated by the head of national security, and, unstable, began to run out of control. The Chief Cabinet Secretary called Yamaki and Riley in, who were successfully able to shut the system down, and were reinstated.
As the Monster Makers worked on creating an ark to bring the Tamers home, Riley contacted all the kids’ parents to let them know they were returning, then asked Janyu Wong about the program used to create the ark. An attack by the D-Reaper on the Hypnos processor almost scuppered the plan, but the Monster Makers were able to corral processing power from computers all across the world, much to Riley’s amazement. The ark Bio-Emerged in Shinjuku Park, and Riley was among the team who were there to see it, regretfully having to report that Jeri’s parents had not come to meet her.
When the D-Reaper followed the Tamers back into the real world, Riley and the other Hypnos and Monster Maker members had to evacuate the Hypnos towers and operate out of a van before moving into a temporary headquarters. Riley, Yamaki and Tally went to meet the Tamers at the Matsuki bakery, where Takato recognised Riley as a regular customer. Riley, Yamaki and Tally then watched as the Tamers’ Digimon battled with a Pendulum Feet, one of the D-Reaper’s Agents.
Riley later consoled Yamaki, realising that he blamed himself for the situation, and telling him that he was just the first person who was trying to control something uncontrollable. Then, she and Tally, along with Shibumi, co-ordinated the Bio-Emergence of Grani.
Riley and Daisy worked together to perform a systems check on Grani, and discovered recorded images from the Digital World, which was now in ruins. As the Digimon engaged the D-Reaper’s Agents again, Riley was successfully able to hack into the D-Reaper’s signal, allowing the adults to see what the D-Reaper saw, including what lay beneath layers of data, revealing to the parents that their children had merged with their Digimon. When the D-Reaper evolved to the Mother D-Reaper, everyone was forced to retreat to Tsukuba, where Riley re-established contact with Johnny Beckenstein, who relayed important information about the D-Reaper’s structure to the team. With that information, the Monster Makers formulated Operation: Doodlebug to disable and devolve the D-Reaper. Riley saw to the activation of the Juggernaut within MegaGargomon, which pulled the D-Reaper through the vortex, back into the Digital World, where it was reverted into it’s harmless original state.
She continues to be a familiar face at Hypnos, even after the digimon are returned to the tamers. During the Demon Lord incident in Book Three, she gets Yamaki to promise to go for coffee afterwards if they should survive. Even though most of the population does not remember the Demon Lords' attack (or the collapse of multiple realities together that follows), they still remember their coffee date.
When Yamaki once more loses his position (this time because of Rayleigh Thompson) and is reduced to assistant for the man, Riley and Tally retain their original jobs. Still, they are limited in their abilities because of Rayleigh's various orders. Eventually, Yamaki loses even that small role at Hypnos and Riley becomes his only source of information on events until he regains his job later on.
During the attack on the tamers in Book Seven, Riley manages to distract the police forces sent to arrest them by throwing a shoe from her high perch. She later escapes with Yamaki, Tally, and Eiichi to the park to meet with the tamers and eventually flee to the Digital World for safety.