[A-PEN68 Development Log] Episode 11: Final Test at Kansai Bass Field

The A-PEN68 prototype also produced impressive fishing results in Lake Biwa.

Refining the A-PEN 68 Prototype on Lake Biwa and Murou Dam

The development of the ADUSTA A-PEN 68 is finally in the home stretch. After dialing in the micro-details—internal structure, buoyancy profile, the single-knock rattle, casting distance, and walking action responsiveness—we needed to take a step back.

Our ultimate goal for this final phase was simple: How do pressured bass react to a compact, single-knocker pencil bait in today's tough fishing conditions? Lake Biwa North Basin Test: A 50cm+ Giant on a Dead-Calm Summer Day

On July 2, 2025, we headed to the North Basin of Lake Biwa with the final prototype of the A-PEN 68. Joining the test was Mr. Kitakata from North Wave, the man who originally sparked the idea for the A-PEN 68 and has been deeply involved since day one.

Conditions on Biwa that day were highly unique.

The humidity was thick—typical of the monsoon season. A light mist hung over the water, blurring the horizon line where the lake met the sky. Most notably, there was absolutely zero wind. The surface was a perfect mirror. Even after fishing the North Basin countless times, I had never seen it look this breathtakingly calm.

Spot 1: The Rocky Bluffs of Takeshima Island

We started scanning the eastern and northeastern rocky walls of Takeshima Island. The area was alive with thick schools of Ko-ayu (landlocked sweetfish), and baitfish activity was through the roof.

Alongside our sales rep, Ambo, the three of us began bombing casts with the A-PEN 68, running through our final checklist:

• Casting Distance & Flight Posture

• Resting Float Angle

• Action Responsiveness (Walk-the-Dog Ease)

• The Single-Knock Acoustic Profile

  
  

As we tweaked the balance, we debated fine details, like, "If it dives any more than this on the sweep, it’ll lose its effectiveness for bass."

Then, out of nowhere, BOOM.

A massive bass tracked the A-PEN 68 from the depths and erupted on Mr. Kitakata’s lure. It wasn't a subtle sip; it was a violent, vertical surface explosion.

Our very first fish of the morning was a 50cm+ hog, fat and healthy from gorging on sweetfish.

That single fish instantly set the tone. Mr. Kitakata smiled and said, "I think you guys nailed it with this one."

High Noon, Slick Conditions: Back-to-Back 50s

When the bite slowed around Takeshima, we moved toward the Kita-Komatsu area to target offshore water intake towers.

Just a few casts into the new spot, Mr. Kitakata’s A-PEN 68 got absolutely choked again. This one was even bigger than the first.

By this time, it was the middle of the day. Dead calm. High water temps. The air temperature was well over 90°F (30°C).

On paper, these are the absolute worst conditions for topwater fishing. Yet, the A-PEN 68 extracted another 50cm+ kicker. This fish proved everything. It showed that this walking bait doesn't just work during low-light golden hours; it has the drawing power to pull fish up through the water column under a blazing midday sun on a slick surface.

The Verdict from Lake Biwa: Two 50cm+ bass under a midday slick. Mr. Kitakata gave it a definitive thumbs up, and we caught the entire proof-of-concept on film.

Size increase in the early afternoon

Murou Dam Test: Cracking the Code on Heavy-Pressure Reservoirs

On June 7, 2025, we took the final prototype to Murou Dam, a reservoir that has become notoriously high-pressure over the last few years. It gets exponentially tougher every season. We wanted to see if the A-PEN 68 could still trigger bites on a crowded weekend.

Early on, the lake looked dead. There was no visible bait activity, so I went back to topwater basics with a strict cadence:

1. Walk the dog 4 times (sharp head shakes)

2. Pause

3. Dead-stick for 5 seconds

4. Repeat

   
   

Right along a tight shoreline wall—CRASH!

A textbook, upward-thrusting blowup. This specific type of aggressive, vertical strike became a massive recurring theme throughout the entire testing phase of the A-PEN 68.

Despite its size, this one bit aggressively.

The Power of the Single-Knock Rattle

We noticed this exact same behavior back in October 2024 during our Yodogawa River tests with Mr. Motoki from Tsunami Lures. We saw it at Lake Biwa, and we saw it again at Murou Dam.

I am fully convinced that a compact profile bait emitting a heavy, deep single-knock acoustic signature triggers a distinct aggression response in predatory fish. They don’t just nip at it—they try to destroy it. It delivers that raw, heart-stopping topwater action anglers live for.

Consistency Across Diverse Fisheries

On July 5, 2025, I returned to Murou Dam with ADUSTA tester Mr. Hemmi. Utilizing a longer dead-stick pause tailored to his style, Hemmi landed a beautiful 45cm+ bass, followed by a handful of solid 40cm-class fish.

The A-PEN 68 had now checked every box across vastly different waters:

• Massive Natural Lakes (Lake Biwa)

• High-Pressure Reservoirs (Murou Dam)

• Major Tidal Rivers (Yodogawa River)

  
  

This isn't a niche lure built for one specific technique. It’s a versatile, everyday topwater weapon designed to perform on your local home waters.

The Engineering Breakthrough: Leaving "Room for Customization"

Developing the A-PEN 68 for freshwater bass brought a massive realization to light: Bass anglers and Saltwater Kurodai (Bream/Chining) anglers want slightly different things out of a topwater walking bait.

It produced some good-sized catches even in high-pressure fields.

When targeting saltwater species in the estuaries, your variables change instantly:

• Water Density: Saltwater vs. Freshwater buoyancy

• Gear Specs: Braided line (PE) vs. Fluorocarbon/Mono leaders

• Rod Actions & Casting Distances

  
  

Bass anglers want a highly responsive, nimble walk-the-dog action that can slide and stall on a dime. Saltwater anglers often prefer a more continuous, splashing stride.

Instead of forcing the lure to fit only one style, we made a calculated design choice: We engineered the A-PEN 68 with "customization headspace."

We tuned the internal weight balance to a razor-sharp baseline. Out of the box, it performs flawlessly for both species. However, by making micro-adjustments—such as changing from a snap to a direct knot, swapping treble hook sizes, or alternating between split ring weights—the angler can instantly tune the buoyancy and swing radius to lean perfectly toward fresh or salt.

It is a true multi-species topwater plug that puts the final tuning hand in the hands of the angler.

The final challenge for A-PEN68 was deciding where to place the quality of the action.

Next Up: The Final Saltwater Chining Showdown

With the freshwater bass testing officially wrapped and approved, the A-PEN 68 moves to its final gauntlet: Boat Chining in Osaka Bay and rugged estuary testing in the Iwakuni area of Yamaguchi Prefecture.

Can one topwater bait truly bridge the gap between Bass and Kurodai? Stay tuned for the next update, where we take the A-PEN 68 into the salt!