Megabass Genma Slim 120S: Specs, 14 Colours and How It Compares With the 110S and 85S

Megabass’s Genma series is a favourite among Japanese seabass anglers, and a new slim model has just arrived: the Genma Slim 120S. Slim sinking pencils are the classic answer to skinny baitfish in winter and spring, so let’s look at the specs and how it differs from the 110S and 85S.

Genma is a sinking pencil series known for the swimming plate at the head, which keeps the action from breaking down when you drift it in current. The new 120 mm slim model is released in November 2026, with some shops stocking it from early November.

Genma Slim 120S specs

Megabass’s official product page did not list a price, so check with your retailer before buying.

The key number is 120 mm at 19.5 g. The Genma 110S is 110 mm at 21 g and 29 g, so the Slim is 10 mm longer yet lighter, meaning it is much thinner. Hooks also change from #4 x 2 on the 110S to #5 x 3: smaller hooks, one more of them, to suit the slender body.

Key features

1. Swimming Keel under the line eye

Under the line eye sits the Swimming Keel (patent pending). Megabass says it delivers three things:

• Quick start-up: swims immediately after splashdown and the first turn of the handle
• Stability: the action holds together in current
• Controllability through resistance: you feel a slight weight, so you can sense depth and current changes

Many anglers dislike sinking pencils because you feel nothing on the retrieve. A lure with a bit of resistance is a real help if you are still learning them.

2. Slim body and rear weight for jig-minnow distance

According to Megabass, the slim body and low, rear-set weight give casting distance close to a jig minnow. A thin profile has less air drag, so it flies well for its weight, useful on beaches and river mouths when you need to reach a distant current line or drop-off.

3. High-pitch roll

The action is a tight, high-pitch roll that flashes to attract fish holding deeper. Being a sinker, you can count it down and work mid-depths and near the bottom as well as the surface.

4. Built for slim bait and worm hatches

Megabass names slender baitfish such as sardine and halfbeak, plus the bachi (sea worm hatch) pattern, as its main uses. Winter-to-spring seabass are often feeding on long, thin bait, so this is exactly the season for it.

Colours

There are 14 colours. Here they are grouped by type:

For your first one, pick a natural colour that matches sardine or halfbeak, such as HT Sayori or GLX Iwashi. For night fishing in harbours and rivers, Joyato Magic (made for areas under lights) is a good choice, and an appeal colour like GG Akakin OB helps in dirty water or at dawn. The grouping above is mine, based on the colour names, not Megabass’s.

How to fish it

• Steady retrieve (slow to medium): the basic method; let the roll do the work
• Drift: let the current carry it, winding only to take up slack. Great around river mouths and bridge pilings
• Countdown: let it sink after splashdown and work through the depths when there is no surface action
• Worm hatch: dead slow just under the surface; the thin silhouette matches the worms

The trick with sinking pencils is not to wind too fast. The keel gives some resistance, so find the speed where you can just about feel the weight.

Genma Slim 120S vs Genma 110S

Megabass calls the 110S a versatile sinking pencil. The 21 g model sways in current for flounder and seabass, while the 29 g version focuses on distance and bottom feel. The Slim 120S matches thin bait better. A simple rule: chunky sardine or gizzard shad, use the 110S; thin anchovy, halfbeak or worms, use the Slim 120S.

Genma Slim 120S vs Genma 85S

The 85S is for inner bays, rivers and canals when fish are on small bait. Choose the 85S for short-range small spots and the Slim 120S when you need distance over a wide area.

Genma Slim 120S vs Duel Hardcore RS12 (S)

Another 120 mm slim sinking pencil worth comparing is the Duel Hardcore RS12 (S), which I covered in my Hardcore RS sinking pencil article.

At the same length, the RS12 is 6.5 g heavier, so it reaches further and deeper. The Genma Slim looks better for slowly showing the lure in the surface to mid layers. RS12 on windy days or in deep water, Genma Slim on calm days and during worm hatches.

Suggested tackle

19.5 g is easy to cast fully on a seabass rod, and an ML–M rod helps you feel small changes in a sinking pencil’s weight. For more on the target species, see my Japanese seabass guide.

My take: a strong pick for winter-to-spring slim bait

When seabass are eating halfbeak, anchovy or worms, a fat minnow or pencil is often ignored. The Genma Slim 120S matches that slim bait while using the keel for stable swimming and feel, and still casts a long way. From the specs, it looks designed as a slim sinking pencil that is still easy to use. It should also work on the surf for flounder and seabass feeding on thin anchovy. Often a sinking pencil catches best when it feels like you are doing nothing, so wind slowly and let the current work.

Summary

• A 120 mm, 19.5 g slim model joins the Genma series in November 2026
• Swimming Keel gives quick start-up, stability and feel
• Slim body and rear weight give distance close to a jig minnow
• Matches slim bait such as sardine and halfbeak, and worm hatches
• 110S for bigger bait and versatility, 85S for small spots, Slim 120S for slim bait and distance

MINAGIMAN

JAPAN ANGLER

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Born in 1994. Originally from Hyogo Prefecture, I moved to Iwata City in Shizuoka Prefecture in search of the sea. I am an Enshunada surf angler who enjoys surf fishing. I am also active on YouTube, and my fishing grounds range from Irago to Iwata.