Who Is k4sen?

Last updated: October 2026

Name (Japanese)	k4sen（かせん）
Born	September 15, 1991 (Osaka Prefecture, Japan)
Category	Streamer / Event producer
Active since	Around 2010 (as a game caster)
Affiliation	ZETA DIVISION, creator division (since September 2021)
Known for	"The k4sen" streamer events, League The k4sen (LTK), The k4sen Con
Platforms	Twitch (main) and YouTube, each with more than one million followers as of 2026

k4sen (pronounced “kah-sen”) is a Japanese streamer, game caster and event producer, and one of the most prominent figures in Japan’s live-streaming scene. He belongs to the creator division of ZETA DIVISION, a Tokyo-based professional esports organization, and broadcasts mainly on Twitch while uploading videos to YouTube. As of 2026, both his Twitch and YouTube channels have passed one million followers.

What sets k4sen apart from most streamers is his work behind the scenes. The invitation-only events he produces under the “The k4sen” banner bring together streamers, VTubers (performers who appear online as animated avatars) and even mainstream celebrities, and they are widely credited with fueling a League of Legends boom among Japanese streamers in the 2020s.

Rise to Fame

Born in Osaka Prefecture on September 15, 1991, k4sen started out around 2010 as a game caster, commentating community tournaments in Japan’s Call of Duty scene. His breakthrough came in November 2012, when commentary videos on Call of Duty: Black Ops II that he posted to Nico Nico Douga — the video-sharing site that shaped much of early Japanese internet culture — spread rapidly and made his name known far beyond the CoD community. He opened his YouTube channel in October of that same year.

Over the following decade he combined broadcasting with production work. In October 2018 he founded Denei Lab. (電映Lab.), a small video-editing company, and became its CEO. Around February 2021 he moved his main streaming activity to Twitch, and in September 2021 he joined ZETA DIVISION as a streamer in its creator division.

What k4sen Is Known For

Since 2022, k4sen has produced a steady stream of events whose concept is disarmingly simple: he picks a game he wants to play and invites the people he wants to play it with. The casts mix famous streamers, VTubers, former pro players and occasionally mainstream celebrities, giving the events a broad crossover appeal. His main projects include:

The k4sen — the original invitation-only event series, covering whatever game k4sen is currently into, from shooters to party games
League The k4sen (LTK) — a season-based League of Legends championship for streamers, launched in 2025 and supported by Riot Games, which grew out of the LoL editions of The k4sen held since 2022
The k4sen Con — an offline fan festival held annually since 2024, where event segments are performed live on stage in front of thousands of attendees

His League of Legends events in particular are credited with introducing the game to a new generation of Japanese streamers and viewers. In recognition of this work, k4sen received the Best Esports Creator award at the Japan eSports Awards 2023, with the ceremony held on January 25, 2024. In September 2025, his YouTube channel passed one million subscribers, just under thirteen years after it opened.

Recent Years

Since 2024, k4sen’s events have steadily moved into the physical world. The first The k4sen Con took place in October 2024 at Ariake GYM-EX in Tokyo, and the 2025 edition ran for three days at Tokyo Garden Theater in November 2025. On the online side, League The k4sen launched in 2025 with the “Spirit Blossom Beyond” season and has since run multiple seasons, eventually organizing its players into three tiers (MASTERS, CORE and NEXT); actress Tsubasa Honda made a surprise entry in the autumn 2025 “Trials of Twilight” season.

The momentum has continued into 2026. The third The k4sen Con was held on August 8 and 9, 2026 at the first arena of Yoyogi National Gymnasium, a landmark Tokyo venue originally built for the 1964 Olympics, with the whole event streamed free on Twitch. As of October 2026, the next big project on the calendar is the LTK season “Finale,” scheduled to run from October 15 to November 22, 2026. Between these large productions, k4sen continues to stream regularly on Twitch, where his day-to-day broadcasts range from new releases to long-running favorites.

FAQ

What is "The k4sen"?

It is an invitation-only event series produced by streamer k4sen since 2022, in which Japanese streamers, VTubers and other guests team up to play a game k4sen has chosen. Its League of Legends editions grew into League The k4sen (LTK), a seasonal streamer championship supported by Riot Games, and the series also has an annual offline festival called The k4sen Con.

Is k4sen part of ZETA DIVISION?

Yes. k4sen joined ZETA DIVISION, a Japanese professional esports organization, in September 2021 as a member of its creator division — meaning he is signed as a streamer and content creator rather than as a competing pro player.

Is k4sen married?

Yes. k4sen has publicly shared that he married his partner, known as Ajaka, in June 2021. Beyond that, he keeps most of his private life out of the spotlight.