2026.09.21 2026.09.22

Shimano Silent Assassin: Every Model Explained (80 to 160, Flash Boost vs Jet Boost)

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The Silent Assassin is one of those lures you see in every Japanese angler’s box, and one of the few Japanese seabass minnows that actually turns up in tackle shops outside Japan. The problem is the lineup. There are now more than fifteen variations, three different “Boost” technologies, and names like Dive Assassin and Slim Assassin that sound like different lures but share the same DNA.

I fish the surf on Japan’s Enshunada coast and the Silent Assassin has been a first-choice minnow there for years. This is a walk through the whole family – what each size is for, what the Boost technologies actually do, and which one I would buy first.

Contents

What the three “Boost” technologies actually do
The lineup at a glance
Model by model
Which one should you buy first?
Buying one from outside Japan
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What the three “Boost” technologies actually do

Flash Boost

A reflector plate suspended inside the body on a spring. It keeps shimmering even when the lure is completely stationary. It comes into its own in daylight, but it still works at night around lit areas or under a full moon.

Jet Boost

Shimano’s weight-transfer system. The moving weight is supported by a shaft and spring, which is aimed at three things: initial speed off the rod tip, a stable attitude in flight, and a quick start to the swimming action after landing. In practice it means you can cast a long way without a perfect casting stroke. Most Flash Boost models also carry Jet Boost.

Scale Boost

The holographic scale finishes. There are three patterns: kyorin (狂鱗), which reproduces the scales of a real sardine in fine detail; kyorin (強鱗), a bolder large-scale hologram; and torin (透鱗), a translucent finish. Colour codes on Japanese packaging refer to these.

The lineup at a glance

Model	Length	Weight	Type	What it is for
Silent Assassin 80S Jet Boost	80 mm	–	Sinking	Small-bait situations, rivers and shallow bays. Fast enough to use like a vibration lure.
Silent Assassin 80F / 80S Flash Boost	80 mm	–	Floating / Sinking	Wide body, square lip, flat-sided flash. Fast retrieve to trigger a reaction.
Silent Assassin 99F Jet Boost	99 mm	14 g	Floating	The all-round search bait. Stronger lip than the old model.
Silent Assassin 99S Jet Boost	99 mm	17 g	Sinking	Longest casting of the 99s. Boil shooting and deeper lanes.
Silent Assassin 99SP Jet Boost	99 mm	15-16 g	Suspending	Rare in a seabass minnow. Strongest action of the three – dirty water, heavy bait.
Silent Assassin 120F	120 mm	19 g	Floating	Slim silhouette, 60 m-plus casts. A versatile size.
Silent Assassin 129F / 129S	129 mm	–	Floating / Sinking	The distance weapon. Probably the most-used minnow on Japanese surf.
Silent Assassin 140F / 140S	140 mm	–	Floating / Sinking	Average cast 71.3 m (sinking, Jet Boost). For fish feeding out of normal range.
Silent Assassin 140S North Premium	140 mm	–	Sinking	Trout-specific version with a bone-reinforced body for northern sea-run fishing.
Silent Assassin 160F	163 mm	32 g	Floating	Biggest in the family. Three #3 trebles, 62 m cast, runs 0.4-0.8 m.
Dive Assassin 99F / 99S	99 mm	–	Floating / Sinking	Diving minnow to roughly 2 m. About 55 m (F) and 60 m (S).
Dive Assassin 125S	125 mm	–	Sinking	Long bill, holds a mid depth under surface bait schools.
Shallow Assassin 99F	99 mm	14 g	Floating	Runs 10-30 cm. 59 m cast. A strong flounder lure.
Strong Assassin 125F / 125S	125 mm	25 g / 27 g	Floating / Sinking	Heavy-duty version for big seabass, hirasuzuki and pelagics. #2 x 2 hooks.
Slim Assassin 149F / 149S	149 mm	–	Floating / Sinking	AR-C SHELL body, 60 m-plus, runs 30-40 cm. Responds well to jerking.

Dashes are where Shimano does not publish a single figure across the sub-models, or where the number differs by colour and hook spec. Where a casting distance is quoted it is Shimano’s own test figure, not something I measured.

Model by model

80S Jet Boost – the small one that is not a finesse lure

Easy to cast into wind and easy to place accurately. The wobble-roll is tight rather than wide, and the response is quick. It swims without blowing out even in fast current, and the resistance through the rod is light enough that you can fish it fast all day. I use it more as a vibration substitute than as a minnow. As a sinking lure it is simple to control the depth, which makes it a good daytime river lure and a searching bait in shallow inner bays.

80F / 80S Flash Boost – a small lure with a big flat side

The body is wider than the standard 80, so the flat surfaces are larger and the Flash Boost has more to work with. Despite the 80 mm body it also carries Jet Boost, so it casts far beyond what the size suggests. The square lip gives it a shallow-crank style wobble, which means a fast retrieve turns it into something close to a vibration. Sinking for fast retrieves, floating for night work.

99F / 99S / 99SP – the size most people should start with

The 99F is the search bait that works regardless of field or conditions. The old model had a weak lip; the current one is noticeably tougher. The 99S adds weight for the spots the floating model cannot reach and for shooting at boils. The 99SP is the odd one out – a suspending seabass minnow is rare in Japan – and it has the strongest wobble-roll of the three, which is what you want in stained water or when there is so much bait that your lure needs to stand out.

In the Flash Boost versions Shimano quotes a swim attitude of 10 degrees for the 99F, 15 degrees for the 99S with a sink rate of 32 cm per second, and 13 degrees for the 99SP. The 99S is the longest caster in the series.

The 80S Jet Boost and the 99F/99S/99SP Jet Boost are the 2026 additions to the range, so these are the versions you will see arriving in shops now.

120F – the quiet all-rounder

120 mm and 19 g in a slim body, and it holds 60 m casts consistently. A soft ML to M spinning rod suits it; swing it like a pendulum rather than hitting it hard and the distance comes. The lip is on the large side but it barely rotates in flight. Slow retrieve gives a clean roll, faster gives a moderate wobble-roll. If you want one Silent Assassin that does a bit of everything and is forgiving to fish, this is the one I would hand a beginner.

129F / 129S – the one I reach for on the surf

This is the longest-casting minnow I have personally used. With an 8’6″ ML rod I get around 50 m; with the 9 ft M-class rod it is really designed for, more. The wobble-roll is obvious enough to pull fish up in open water, even where there is depth under it. You can catch on a straight retrieve and nothing else.

The Flash Boost version is a shallow runner working just under a metre, with a crisp but not excessive action. It covers seabass, flounder, hirasuzuki and pelagics, and on Japanese surf it is the lure I see in other people’s hands more than any other. If you are choosing a 12-13 cm shallow runner and cannot decide, start here.

140F / 140S – for fish out of range

Boils, tide lines and bird activity often sit beyond minnow range. Jigs and vibration lures get there but the depth or action is wrong. That is the gap the 140 fills: Shimano quotes an average of 71.3 m for the sinking Jet Boost version, and 66.4 m / 67.4 m for the Flash Boost floating and sinking models using the AR-C system. In use it swims properly off rocky shores, surf and big rivers alike, and it holds up in a headwind. The red head is the colour I would buy first.

160F – the big-bait answer

163 mm, 32 g, floating, three #3 trebles, 62 m casting, running 0.4-0.8 m with a 5 degree swim attitude. It is built for seabass eating mullet, gizzard shad or falling ayu, and the three hooks are there so a big fish thrashing at the surface stays attached. Japanese list price is 2,380 yen excluding tax.

The spin-offs: Dive, Shallow, Strong and Slim

Dive Assassin 99 reaches about 2 m – offshore breakwaters, rock fishing for hirasuzuki, and daytime boat seabass. The long lip catches air, but Jet Boost still gives roughly 55 m floating and 60 m sinking.

Dive Assassin 125S is for when bait is stacked on the surface and the fish are just under it: it keeps a middle depth without snagging the bait ball, and it casts well enough to cover from your feet to the horizon.

Shallow Assassin 99F is 99 mm and 14 g, runs 10-30 cm, casts 59 m, starts swimming from 40 cm per second and sits 10 degrees nose-down. It has a strong record on flounder.

Strong Assassin 125F / 125S is the heavy-duty build: 125 mm, 25 g floating and 27 g sinking, #2 x 2 hooks, 2,400 and 2,450 yen. Appeal, durability and distance in one lure – it is the one for washing white water on rocky shores and for big fish generally.

Slim Assassin 149F / 149S uses the lightweight AR-C SHELL body with the AR-C weight transfer system for 60 m-plus casts. It runs 30-40 cm down with a relaxed pitch and a bigger roll angle, and it responds well to rod work as well as a straight retrieve.

Which one should you buy first?

One lure, general saltwater: 120F. Easy to cast, easy to fish, covers most situations.
Surf and open beaches: 129F. Distance is what wins on a beach and this is the distance lure.
Shallow flats and flounder: Shallow Assassin 99F.
Small bait, rivers, inner bays: 80S Jet Boost.
Big fish, rocky shores, pelagics: Strong Assassin 125.

Buying one from outside Japan

Most of these are sold under the Exsence brand in Japan, so the box will say “EXSENCE Silent Assassin” with a model code such as XM-140N. The Jet Boost and Flash Boost versions of the same size are different lures with different prices, so check the code rather than the picture. Japanese prices quoted here are domestic list prices excluding consumption tax; what you pay abroad will be higher.