Gomez's Tank Secret Waterfall Base

Start in Riorad Village: This is your starting hub. Make sure to explore the village thoroughly – check those wooden boxes and drawers for any useful items. Once you're ready, head southeast to the South Cave.

South Cave and getting the 'Mosquito' Tank: Inside the South Cave, keep an eye out for more items in the boxes. You'll eventually reach B2 where you'll face the boss, Bionic Pooch. Don't sweat it too much; Red Wolf's tank shows up to help you out. After the fight, interact with the computer, select 'search,' and then 'gate control.' Choose 'OPEN' and hit A twice. Now, head to your tank, select 'get on and get off,' then 'get on,' and finally 'end.' This tank is your new ride, the 'Mosquito.' Drive it northwest to the North Cave.

North Cave and the Salmonella Family: Drive Mosquito through the North Cave, grabbing any items you find. Be careful on B3 with those holes near treasure chests – you might want to come back for those later if they overload the tank. On B4, you'll face the Salmonella Family x2. After you defeat them, you'll get 'monster badge one.' Head out of the cave and north towards the Northern Barrier. You can always pop back to Riorad Village for supplies if needed.

Northern Barrier and ID Card: At the Northern Barrier, get off Mosquito. Head into the room with the TV and talk to the guy on the right. Say 'yes' to get the 'ID card (c).' Now, go to the computer in the top-right room. Use your partner's tools to select the 'ID card (c)' and 'use it' to open the gate control. Get back on Mosquito, drive through the gate, and head east to Negi Village. You can walk into Negi Village to avoid any potential issues with Mosquito on certain terrain.

Negi Village and the Wedding Ring: In Negi Village, explore the potato field in the lower right corner. Interact with it four times, saying 'yes' each time, to cultivate it and get the 'wedding ring.' Find the girl in the kitchen of a nearby house and give her the ring. She'll give you the 'ruby lens (1-4).' After grabbing any items in the village, get back on Mosquito and drive southeast to Bobre Opre Town.

Bobre Opre Town and Masakazu: This town is a major hub. Stock up on gear at the equipment shop and check for items. If you donate to the school, a statue will be built. Head to Uriu-san's House nearby. Go inside and through the door on the right for an event. Afterward, find the mechanic Masakazu driving Mosquito outside. Talk to him, say 'yes' twice, and he'll join your crew. Grab any items and then drive Mosquito east to the Seashore Factory.

Seashore Factory and the Wild Buggy: Go up to the 3rd floor of the factory and talk to the President on the balcony twice, saying 'yes' both times. This grants you permission to use the 'wild buggy.' On 3F, have Masakazu get on the buggy, then use the menu to 'get on and get off' and 'get on.' Now you have the Buggy! Use it to navigate through ledges and holes until you reach 1F. Once on 1F, have the Hero get on Mosquito. Drive across the iron bridge, and you'll face the 'Dos Piranas and frogman x2' boss. After the fight, you'll get another monster badge. Drive both vehicles back to Bobure Opre Town.

Bobure Opre Town (Supplies) and Cannon Gun Position: Back in Bobure Opre Town, visit the tank curio dealer to buy a 'dug system' for Mosquito (it's like a warp). Also, grab 8 armor-piercing rounds from the cannon ball shop. Head north of Negi Village through the exploding field to reach the Cannon Gun Position.

Cannon Gun Position and Big Cannon Boss: Drive into the position with the two large cannons. Go through the gate and fight the first 'Big Cannon' boss. Use the armor-piercing rounds to stun it during the battle. After defeating it, use the 'dug system' on Mosquito to warp back to Bobre Opre Town for more supplies. Return to the Cannon Gun Position, drive further in, and fight the second 'Big Cannon' boss, again using armor-piercing rounds. After this, head northeast to Audrey Town.

Audrey Town and Jean: In Audrey Town, head to the building on the top left and go downstairs to the bar. Find the female soldier Jean and talk to her, saying 'yes' twice. This will trigger a battle against the 'Bad Group x6.' After you win, Jean will join your group. Speak to her again to confirm she's with you. In the bar, go down the ladder on the bottom left to the transmission center. Use the computer there, select 'search,' then 'transmission,' and choose '2' to open a transmission door. Walk into the chamber, and you'll warp to Negi Village.

Negi Swamp and Dr. La Flecha: Exit Negi Village and head into Negi Swamp. Just navigate through the swamp until the boss 'Dr. La Flecha' appears. Defeat him to get another monster badge. Head back to Negi Village.

Negi Village (Transmission) and Warp to Audrey Town: Back in Negi Village, go to the transmission center, use the computer, and select 'search' then 'transmission.' Choose '4' to open another transmission door. Step into the chamber, and you'll warp to Audrey Town.