What begins as a mischievous plan from the Bearmon brothers quickly spirals into a small adventure beneath Central Town, leading players to confront one of the game’s slyest Digimon. This guide provides an insightful, step-by-step walkthrough of the mission from unlocking the quest to the final battle, ensuring you capture every reward and understand the lore that glimmers beneath its surface.

Quest Overview

Client: Big Bearmon
Location: Central Town – Downtown
Mission Summary: Help the Bearmon brothers recover the stolen jewelry from PlatinumNumemon.
Rewards:
- 3,000 Yen
- 45 Anomaly Points
- CRT Attachment I ×1
- Courage Point I ×2

How to Unlock PlatinumNumemon’s Jewelry

This side quest becomes available after you’ve progressed through the “On the Shores of Another World” main mission. Upon completing the Between the Worlds side mission, you’ll receive a Digiline message from Big Bearmon, hinting at a “heist” involving PlatinumNumemon’s jewelry.

The player character standing in a bright, colorful section of Downtown Central Town with the mission objective "Talk to Big Bearmon" displayed on the screen, showing the location where the quest begins. — Credit: Bandai Namco Entertainment

The message marks the beginning of a lighthearted yet challenging detour that ties into the Bearmon brothers’ mischievous streak — and your role as the responsible Agent keeping them out of real trouble.

Step-by-Step Walkthrough

1. Meet Big Bearmon in Downtown Central Town

Head to the western side of Central Town, near the Downtown district. You’ll find Big Bearmon and his younger brother excitedly plotting their underground venture. Speak to them to learn about their plan to retrieve PlatinumNumemon’s lost jewelry — or rather, “borrow” it back.

When you’re ready, agree to join their little expedition and follow them underground.

The player character talking to Big Bearmon in the underground area near the stairs, where Big Bearmon is seen smugly stating, "Oh, look who it is. Well, guess what? I found somebody way better than the likes of you!" — Credit: Bandai Namco Entertainment

2. Follow the Bearmon Brothers Underground

Slip under the broken fence nearby to access the Spiral Waterway, the damp and maze-like sewer beneath Central Town. Inside, follow the path until you find the Bearmon brothers cornered by three Geremon.

This triggers your first major encounter.

3. Battle – Geremon ×3

The Geremon trio are Level 18 Virus Attribute / Mollusk Type / Champion-class Digimon.

They’re particularly weak to Fire and Electric attacks and resistant to Earth and Steel.

Recommended Digimon:

Agumon (Fire)
Biyomon (Electric/Fire)
Tentomon (Electric)

Use Vaccine-type Digimon to gain an elemental advantage, and keep a few paralysis recovery items handy — Geremon’s Hyper Smell attack can lower SPI and inflict paralysis.

4. Gather Clues at the Tavern

After the battle, you’ll be automatically transported back to Downtown.
Your next stop is The Warrior’s Watering Hole, a tavern on the northeast side.

Inside, talk to Deputymon, the sharp-tongued bartender who knows more than he lets on. He hints that PlatinumNumemon was last seen “deep underground” — a misdirection that may confuse unprepared players.

He’s only half right, so pay attention to what happens next.

5. Return to the Spiral Waterway

Travel back to the Spiral Waterway. Initially, the deepest chamber will appear empty. Don’t be fooled. Turn around and make your way back toward the entrance of the Waterway.

This clever misdirection triggers PlatinumNumemon’s appearance — a classic trickster move fitting for such a Digimon.

6. Battle – PlatinumNumemon

Once you return to the entrance, PlatinumNumemon emerges, ready for battle. This opponent is a Level 18 Virus Attribute / Mutant Type / Mega-class Digimon, known for its evasive maneuvers and irritating status inflictions.

Weakness: Water
Immunity: Electric

Recommended Digimon:

Gomamon (Water-type attacks)
Monodramon (Earth-type attacks)
Tapirmon (support and recovery skills)

Battle Strategy:
Use Water-based attacks to exploit its primary weakness, and bring items to counter Poison and SPI-reducing effects. When its HP drops, PlatinumNumemon may try to flee — keep your attacks quick and decisive.

The player character and their Digimon partner, HolyAngemon, standing over the defeated PlatinumNumemon in a dark corridor, with a text box confirming "Obtained PlatinumNumemon's Jewelry." — Credit: Bandai Namco Entertainment

7. The Decision: Trade or Give Away the Jewelry

After defeating PlatinumNumemon, you’ll obtain its precious jewelry. Upon returning to the Bearmon brothers, you face a choice:

Give it to them for free (earn goodwill but no special bonus), or
Trade it for the Aura Skill Disc, an early-game item that grants a valuable party-wide healing ability.

For practical purposes, trading is the wiser choice — the Aura Disc can sustain your team in tougher battles later on.

Rewards Recap

Item	Quantity	Description
Reward Money	3,000 Yen	Standard currency reward
Anomaly Points	45	Increases Agent progression
CRT Attachment I	×1	Increases critical rate
Courage Point I	×2	Boosts Digimon stats temporarily
Aura Skill Disc	Optional	Healing skill disc if you trade the jewelry

Tips for Success

Bring Status Recovery Items: Both Geremon and PlatinumNumemon love using SPI-reducing and Poison attacks.
Use Cross Art: Burst: Once you’ve built enough CP, this guarantees a strong hit against PlatinumNumemon’s evasive nature.
Don’t Rush the Underground Sequence: Missing the turn back at the entrance may cause confusion; PlatinumNumemon only spawns once you retrace your steps.

More Trending Game Guides: