The edge of a knife is usually more or less shaped like a V, with sides tapering to a sharp point. But the angle of that V can make a huge difference in how a knife performs.
The classic Western-style chef’s knife typically has an edge angle of around 20 degrees on each side of the vertical axis. (That is to say, the tip of the V is a 40-degree angle in total, but commonly knife people talk about the single edge angle.) Japanese knives are more typically sharpened to a narrower angle of around 15 degrees.
What’s this mean in practice? The 20-degree Western edge is more resistant to wearing down and bending over [link to honing article], while the narrower 15-degree Japanese angle feels sharper and cuts a more deftly, all else being equal. But since there’s less metal there, it tends to dull more quickly.
To compensate, many Japanese-style knives are made from harder steel [link to steels article], which doesn’t wear down as easily. Some knives in this category also have a “single bevel”—that is, one side of the knife edge’s V is vertical, and the other one meets it at a narrow angle. This asymmetrical construction is extra sharp, but difficult to sharpen.
What about Misen knives? By combining a 15-degree edge angle (from Japanese-style knives) with the hard, durable steel and symmetrical grind of a Western-style blade that’s suitable for both right- and left-handed cooks, Misen knives were designed to combine the best of both worlds.