Kogetsu

"The most popular, all-purpose blade: Kogetsu."

- Shiori Usami

is an Attacker Trigger.

Appearance
Kogetsu is a slightly curved with a luminous yellow blade and no guard. Its gray handle, which is long enough to accommodate two hands, is composed of a series of rectangular tassels and a wider portion roughly one inch long between the grip and the blade. Its scabbard is plain and generally worn with the cutting-edge down.

Yūko Kumagai had her Kogetsu modified to include a cross-shaped tsuba, Kirie Konami to shorten the blade. Yōsuke Yoneya customized his into a sankaku yari, a gray spear measuring roughly six feet in length with tassels much like the regular model's making its shaft easier to grip at the butt and right before the tip, two-fifths of which are hollowed out. Kō Murakami had the color of his Kogetsu changed to black before round seven of the current season of Rank Wars.

Overview
Kogetsu was the first Attacker Trigger to be developed. The members of Old Border appeared to be already equipped with it at the time of the First Large-Scale Invasion.

Abilities
Kogetsu is considered an all-purpose Attacker Trigger as well as the most balanced one, boasting both high offensive power and durability. It is capable of effortlessly slicing through matter not made out of Trion, including metal poles and concrete walls several dozens of centimeters thick, and trion bodies alike. A single swing can crack a Scorpion or even break a transformed one, and Aftokrator's armored capes offer no protection against it. Although a focused Shield is generally a viable defense, it can be cracked and broken within a short time frame with continued pressure and possibly a high level of skill. However, the barriers generated by an Idra can withstand a high-speed slash. Kogetsu itself is very durable, and it has yet to be seen so much as chipping after repeatedly clashing against itself or any other blade; thus far, only Ikoma Senkū has succeeded at cleaving through both a deactivated Kogetsu and its scabbard.

Unlike Scorpion and Raygust, Kogetsu cannot shapeshift without its Exclusive Optional Trigger Gen'yō. Senkū, a second dedicated Optional Trigger, can briefly extend its blade for vastly increased reach and cutting power. These Triggers are equipped to the same hand as Kogetsu, thus they can be activated while two Triggers are already in use. Kogetsu itself can be turned off in order to use other Triggers without the need to dispel it or put it back in its scabbard, but it will lose its edge completely until selected again. To prevent it from becoming a burden, one may decide to destroy the blade and the sheath and conjure them anew when needed, but the process will consume trion. A new blade can be materialized after the previous one is lost or becomes unfit for use and made to appear inside the pre-existing scabbard.

One of the few downsides to Kogetsu is its weight. The majority of users find themselves off-balance when wielding it with only one hand, and underperform as a result of their swordplay getting slower. However, there are also particularly capable agents who prefer to brandish it with only one hand, presumably suggesting that skill can offset the Trigger's weight. A very circumstantial drawback of Kogetsu is that it has a luminescent blade, which can be easily spotted in the darkness; however, the glow can be removed by setting its color to black with the help of an Engineer. Since it interferes with Lead Bullet, Kogetsu is in all likelihood a physical object.

Users
There are 28 known agents with at least one Kogetsu chip in their Trigger Set. The number rises to 29 if Yōsuke's spear, which has a slightly different name, is classified as a customization and not a separate Trigger. No. 1 Attacker and solo combatant Kei Tachikawa is an especially noteworthy user, as is his teacher, Director Masafumi Shinoda, hailed as the strongest normal Trigger user at HQ. Kogetsu is also used by an unknown number of trainees and agents who do not take part in rank wars.

Particularly notable among former users are Kirie Konami, who surpassed even Tachikawa in points before withdrawing from rank wars, Yūichi Jin, previously the no. 2 Attacker and solo combatant, and Raizō Terashima, a high-ranking Attacker who became an Engineer.

Trivia

 * The author confessed that the sudden disappearance of a Kogetsu is due to him forgetting to draw it.
 * The concept of a black Kogetsu was teased by the author in the official databook prior to its appearance in the series.