Renamon first met Rika Nonaka when she won the Digimon Championship and arrived home, lot of Digimons tried to be her partners, but she only wanted one strong one. The others then made way to Renamon and Rika wished her to be real. The two then started a quest to gain more power, they fought various Digimon who preached the gap between two worlds.
Mayor Story Arcs
At first Rika thought digivolution would occur when Renamon absorbs strong data from defeated Digimon, but learned that to be wrong when Renamon first digivolved to Kyubimon when she protected Rika from Dokugumon. Rika had trouble believing that emotions are the base for digivolution, and they drifted apart with Renamon. After Rika was kidnapped by Icedevimon, who wanted to be her new partner, the gap between Rika and Renamon grew and they stopped being partners. When Renamon fought Harpymon alone and was about to lose, Rika rushed to her help and the two finally admitted their feelings for each other.
After their first run-in with the Deva, Mihiramon, Digimon Tamers agreed to join forces to destroy other Devas. The fourth and fifth Deva they met were Vajramon and Pajiramon. They managed to destroy Pajiramon when Terriermon digivolved to Rapidmon. After the battle, Renamon left with Vajramon to learn about Devas plans. It also seemed that Vajramon had a crush on Renamon and tried to convince her to join Digimon sovereign to overtake the earth. It was there Renamon digivolved into Taomon for the first time and defeated Vajramon, declining his offer.
After defeating 8th Deva Vikaralamon, Calumon was kidnapped and taken to the Digital World. Digimon Tamers decided to go there and save him. Before they left Renamon was discovered by Rika's grandmother, but she took it rather well and made Renamon promise she'd protect Rika. After their arrival Renamon and Rika got separated from the main group when they chased after Kazu and Kenta and got sucked into a data-stream. On their search to locate others they found another human, Ryou Akiyama, Rika didn't quite like him and decided to go solo for a while. Renamon and Rika found lost Calumon and found a way to join others, but it was then that things tuned worse. Calumon was again kidnapped and Henry Wong and Takato Matsuki, got separated from the group.
Renamon and others were reunited in a battle against Impmon, who now was digivolved to Beelzemon. He was on mega-level and Renamon in her Kyubimon form was no match for him, and was badly beaten, just as Beelzemon was about to kill Kyubimon, Leomon stopped him and was killed for it. Beelzemon was finally defeated when Takato and Guilmon bio-merged. Next battle they head was against the sovereign who sent all those Devas against them. But it turned out that he only wanted to save Digital World and they ended up joining forces, to save Calumon. It was Rika and Renamon, who again found Calumon and saved her, but their path was blocked by Chaos of D-Reaper. It was then Renamon and Rika took a leap of faith to save Calumon and bio-merged for the first time to Sakuyamon. They hold of the Chaos long enough for everyone to escape it path. Then it was time to go home, but before that Renamon sensed Impmon nearby and wanted to save him, Rika agreed with her and they went to find him. They made it back to the Arc just in time for it to leave for Earth.
Back on earth they found out that some of the Chaos matter piggybacked a ride with them, and three friends again joined forces to defeat it. Renamon and others met Dobermon, who gave them a gift from Digimon Sovereigns to bio-merge in real world with their human partners. After their valiant effort Digimons and their tamers were able to defeat D-Raper. In the end all the Digimon de-digivolved and needed to return to the Digital World.