Mamon King, a monster-raising indie game by LiTMUS and co-produced with Japanese gaming YouTuber Yoshinama, exceeded expectations by selling about 60,000 copies in the first nine days after launch, driven by a collaboration that amplified visibility.

The title, inspired by Monster Rancher, surged to 60,000 copies within the first week, with strong momentum from Yoshinama’s involvement and cross-promotion.

Looking ahead, the team plans a game update to expand gameplay systems, reinvests Yoshinama’s earnings into a stronger follow-up title, and is pursuing a physical Nintendo Switch edition for boxed release later.

In addition to the update, Yoshinama intends to reinvest proceeds to create an improved next project, sustaining the momentum.

Streaming and grassroots promotion were pivotal, with fans outside the official collaboration driving discovery and underscoring indie-driven word-of-mouth and streamer culture.

The game quickly topped Japan’s Steam Top Sellers and was the second most-downloaded software on the Japan My Nintendo Store at launch, signaling strong cross-platform interest before settling into longer-term rankings.

Initial success saw the game reach the top of Steam Japan and second on My Nintendo Store, before it cooled to 91st on Steam and 41st on My Nintendo Store.

Yoshinama personally invested 25 million JPY (about $160,000) of his own money into the project, catalyzing interest and helping persuade LiTMUS to pursue the collaboration.

That personal funding, despite limited game-development experience, helped shape the project and attract participation from LiTMUS.

Both developers credit Yoshinama’s strong community as a major driver of sales, expressing astonishment at the first-week numbers and appreciation for player support.

Mamon King is available on Windows via Steam and on Nintendo Switch, ensuring accessibility across platforms.

LiTMUS’s Yu Totsuka initially deprioritized Mamon King, but shifted to support the project after witnessing Yoshinama’s determination and the momentum of the community.