A thread on 5ch shared a video of someone slowly test-cutting a paper carton with a Japanese sword (katana). While some viewers were struck by how the blade was worked in with small, repeated motions instead of one swift slash, others gave a cooler response — “anyone could do that,” “even a kitchen knife could manage it” — sparking debate over just how sharp the blade really was.
Reminds me of Bucciarati getting punched (the famous 'gets beaten up' scene from JoJo's Bizarre Adventure)
14AnonymousAug 23, 2026 22:37
Re: #9
The pain hits you in slow motion, delayed lol
11AnonymousAug 23, 2026 22:36
Still, cutting through an empty, unsecured carton without knocking it over might actually show insane sharpness
13AnonymousAug 23, 2026 22:37
Some slacker old man scraping by doing street performances
16AnonymousAug 23, 2026 22:39
I thought he was just holding his stance the whole time, but he'd already cut it lol
17AnonymousAug 23, 2026 22:39
Kind of like those old warrior legends where a dragonfly lands on the blade and just splits in two on its own — does that kind of thing actually happen?
19AnonymousAug 23, 2026 22:40
He's sawing it in with terrifyingly tiny little motions
Only someone as sharp-eyed as me would even catch that
20AnonymousAug 23, 2026 22:43
This is the thing people do before and after sharpening a kitchen knife
21AnonymousAug 23, 2026 22:43
Wait, he's doing it slowly?! lolololol
22AnonymousAug 23, 2026 22:43
Before I knew it, it was already cut clean in half
25AnonymousAug 23, 2026 22:44
Well, it's not easy, but a katana's edge should manage at least this much
27AnonymousAug 23, 2026 22:45
Cutting it slowly is actually the harder part, but this isn't really what I wanted to see
28AnonymousAug 23, 2026 22:45
Anyone could do this lol
45AnonymousAug 23, 2026 23:02
Re: #28
Seems doable once you get the knack for it lol
29AnonymousAug 23, 2026 22:45
If this were an iaido quick-draw, you guys would just complain it's too fast to see
31AnonymousAug 23, 2026 22:46
Videos of sword draws too fast for the camera to catch show up now and then
34AnonymousAug 23, 2026 22:48
I used to love those old Katori Shinto-ryu (a classical Japanese swordsmanship school) videos on Niconico, watched them over and over
36AnonymousAug 23, 2026 22:49
I thought I was going to see some inhuman, otherworldly technique like Kogan-ryu (the brutal fictional sword style from the manga Vagabond)…
37AnonymousAug 23, 2026 22:50
Cutting it slowly is actually the impressive part
There's no way I could ever pull that off
39AnonymousAug 23, 2026 22:51
Some people are saying it's just moving under the sword's own weight
41AnonymousAug 23, 2026 22:53
Deep down he's probably just dying to cut an actual person
43AnonymousAug 23, 2026 23:00
I was expecting him to cut a small slit at the spout
47AnonymousAug 23, 2026 23:04
Turns out there's no real back-and-forth sawing going on
49AnonymousAug 23, 2026 23:17
There are similar videos out there for sharpening kitchen knives
51AnonymousAug 23, 2026 23:25
He's just adjusting where he applies force so it doesn't tip over
53AnonymousAug 23, 2026 23:32
Does a katana only show its true sharpness in the hands of a master?
I wonder if every samurai back in the day had the skill to bring that out
55AnonymousAug 23, 2026 23:35
They say you have to draw the blade to cut
Well, that's true for paper anyway
56AnonymousAug 23, 2026 23:35
In real combat it was probably more thrusting than slashing
57AnonymousAug 23, 2026 23:42
Apparently it was more like beating people to death than cutting them
Like clubbing them with something more like an iron rod
58AnonymousAug 23, 2026 23:43
Lol, but wait — could this actually be an AI-generated video?
62AnonymousAug 23, 2026 23:48
I wonder what would happen with an OLFA box cutter (a popular Japanese utility knife brand)
63AnonymousAug 23, 2026 23:49
Being able to cut it slowly without knocking over a light, empty carton is probably the impressive part
64AnonymousAug 23, 2026 23:49
No way a kitchen knife could do that
Just think about it for a second
65AnonymousAug 23, 2026 23:50
I have cut a worthless thing again (the famous line from Rurouni Kenshin)
Background and Key Points
Tameshigiri, the practice of test-cutting with a katana, has roots in Edo-period sword appraisal, when blades were tested on rolled tatami mats, bamboo, or even, historically, condemned criminals’ corpses, to certify a smith’s work and a swordsman’s technique. A rolled or soaked tatami mat is the modern standard because its fiber density is said to approximate human flesh resistance; a dry paper carton, by contrast, offers almost no resistance, which is exactly why the video split opinion. Katana blades are ground to an extremely acute, single-bevel edge (often under 15 degrees), very different from a Western kitchen knife’s more obtuse double bevel, so the “any knife could do this” comparisons posters made aren’t quite apples to apples, even if a sharp kitchen knife genuinely could slice an empty carton.
The thread’s real fault line wasn’t sharpness versus dullness, but interpretation of technique: some posters saw slow, deliberate pressure as proof of a bladeless-looking, unimpressive cut (“anyone could do that”), while others (37, 63) argued that cutting slowly, without toppling a light, unsecured, empty box, is actually the harder technical feat, since a fast slash would use momentum to stabilize the target while a slow draw relies purely on edge geometry and controlled force.
What the thread never engages with is that real historical sword combat, unlike choreographed test-cuts, involved armor, thrusting, and blunt trauma far more than clean slashes (briefly noted at 56-57), and that the dragonfly-splits-itself legend mentioned in the thread is folklore, not a documented phenomenon, even for legendary blades like Masamune’s.
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