Two years before Rika met Renamon, she had another partner Digimon, which ended in great tragedy. Back then, she was much different from the all business tomboy she was known as in her teenage years. She was a happy extrovert and partner of a Biyomon, just like from the TV series. She also possessed the digivice and set of cards, but she didn't use them for their real purpose. Back then, Rika saw Biyomon as a friend, not a weapon.
Rika woke up with Biyomon in her arms. She held her like a kid would a stuffed animal. When she woke up, she yawned and sat up. Biyomon rolled over in her sleep, mumbling something about cats. Rika slunk away to take her shower, and when she came back, Biyomon was still fast asleep.
"Hey, sleepyhead." She whispered, nudging the pink bird while she brushed her wet hair. "Wake up. It's time to get up."
Biyomon rolled around in her sleep before finally waking up.
"Huh? Is it morning already?" she asked, rubbing her eyes.
"Of course! Remember we were going to the park today?"
Biyomon's eyes widened and she nodded her head in recollection.
"Oh yeah! I remember now!" she exclaimed, hopping up to her feet. She came up to Rika's waist.
"We'll go as soon as I can finish getting dressed." Rika got dressed in her familiar attire of tight blue jeans and a white and green T-shirt with a broken heart pattern on the chest. Back then, she didn't tie her hair back, and it hung freely down to her shoulders.
"Come on! Let's go!" she said, running out the door. Biyomon followed suit closely behind her.
At the park, as hard as it may sound, Rika actually played with Biyomon. The two raced back and forth across the pathway, with Biyomon winning most of the time. After that, Rika held onto Biyomon as she spread her wings, and she leapt into the air. Biyomon was not able to fly with the added weight, but she was able to glide quite a long distance. When Rika's feet hit the ground, she let go of Biyomon and skidded to a halt, laughing enthusiastically. Biyomon circled around back to the young girl, who caught her in her arms and pulled her into a hug.
"Hee hee! I'm glad I met you, Biyomon!" Rika exclaimed.
"I'm happy, too, Rika!" Biyomon cooed and nuzzled her head against Rika's cheek. The sun was setting, and the two were preparing to head back. Before they could leave the park, however, a heavy fog fell over them.
"What's going on?" Rika asked, looking around them. The fog was so thick; they could barely see the pathway ahead of them. Amid her confusion, Biyomon knew what was happening, and whatever it was, she expressed great discomfort.
"Oh no… Rika, let's get out of here, and quickly!" she exclaimed, pulling on Rika's arm.
"Why? What's happening?" She followed suit behind Biyomon as she led the bewildered human out of the fog. Before they could get out of the park, however, the two were attacked from the gradually darkening shroud by another Digimon. Rika was sent tumbling to the ground as she felt something like tree branches strike her across the chest. The front of her shirt was torn, and she was bleeding underneath, but it was otherwise nothing more than a flesh wound.
"AHHH! Biyomon!" Rika called out into the fog. She could see the silhouette of Biyomon moving about, as if to dodge something attacking her.
"Rika! Run away now! SPIRAL TWISTER!!!" Rika saw a swirl of green fire cut through the fog, missing Rika by only a few inches and striking a tree behind her.
"Wh-What?! You can breathe fire?!" she exclaimed. She was terrified at what Biyomon was fighting in the shroud, and the newly discovered fact about the supernatural powers of Digimon. Biyomon fired off more bursts of fire before being swatted with a spiked branchlike tentacle; the same thing that struck Rika.
"No, Biyomon!" Rika ran over to Biyomon and held her close. Out of the fog came out a large red Digimon with an eggplant shaped body, a vicious face, and green tentacles for arms.
"Wh-what is that thing!?" she screamed, backing away with Biyomon in her arms.
"It's a RedVeggiemon!" Biyomon explained. "They're a really rotten Digimon that you wouldn't want to find in your salad!"
Rika held the pink bird even closer and slid away from Redveggiemon, who slowly bounced towards them – seeing as it had no legs.
"Rika, let me go! Let me fight him!" Biyomon said, struggling in her grip.
"No! I won't allow you! You'll get killed!"
"Rika, listen to me! I can fight him! I have the power to do so! Now let me go!" She bit Rika on the hand, which caused her to lose her grip on the Rookie-level Digimon.
"SPIRAL TWISTER!" Biyomon fired another stream of green fire right in Redveggiemon's face, who ignited and flailed around, trying to put the flames out.
"Now RUN!" Rika reluctantly hopped to her feet and ran in the opposite direction, hoping Biyomon could beat the Digimon. She hid behind a tree and watched through the fog at the duel between the two. The Redveggiemon managed to shake off the flames, and swung his arms wildly at Biyomon. The bird screamed in pain and was sent flying back and forth like a ragdoll.
"NO! Biyomon!" Rika shouted. She found it becoming harder to stay put. Biyomon was sent to the ground quickly, beaten and bruised. She struggled to get to her feet, but couldn't manage, and collapsed. Redveggiemon laughed maliciously, and continued to pound her as she lay on the ground.
Rika couldn't take it anymore. She ran out to Biyomon, swinging her fists at the Champion level Digimon, with futile effort. Redveggiemon merely knocked her aside, and spread open his arms, ready to absorb the data that would rise from Biyomon's body when she died.
"DIAMOND STORM!!!" Before anything could happen, a rain of glasslike shards came crashing down on Redveggiemon, who roared in pain before exploding into a rain of data. It swirled around briefly before vanishing into the fog. Rika crawled over to Biyomon, bleeding from cuts and scrapes on her body. It wasn't life threatening, but Biyomon's injuries definitely looked serious.
"Biyomon!" Rika exclaimed, tears welling up in her eyes. "Please speak to me!"
The Digimon slowly opened her eyes, and lifted a wing to Rika's cheek.
"Please don't cry, Rika." She said weakly. "I don't want to… see you sad."
"Biyomon, I'll take care of you until you feel better, you hear me?" Rika held Biyomon in her arms, hugging her gently to avoid making her injuries any worse.
"No… it's too late for me… please, Rika. Don't cry… I… I love you, Rika…" Biyomon's eyes slowly closed, and her body began to distort and melt into red wisps of data. Rika tightened her grip on Biyomon and held her until her form had melted away entirely.
"NOOOO!!! BIYOMON!" Rika cried. She curled into the fetal position and sobbed, tears streaming down her face. She lost her closest friend, and for some reason, it felt like she died a little as well.
Rika jumped as she felt a warm furry paw press on her shoulder, and she looked up to see a tall anthropomorphic fox with yellow fur and purple gloves.
"NO! Stay back!" she protested, moving to back away.
"Relax, I'm not going to kill you." she – which Rika was able to determine by the feminine voice – answered. "You're my new tamer… Rika."
The event of losing Biyomon was very traumatizing to Rika. She quickly built up a strong cold exterior and became very emotionally isolated, which she became known for 2 years later. She became only interested in becoming stronger, and only saw Digimon as data, to prevent herself from having her heart broken once again, like with her first true love, Biyomon.