In 2004, they were renamed as Matsumoto Yamaga when nonprofit organisation Alwin Sports Project were set up to support the club with the intention of promotion to J.

2008 also brought a crucial Emperor's Cup run, where they defeated former Japanese champions Shonan Bellmare in the third round by penalty kicks, only to be eliminated 8–0 by Vissel Kobe.

The 2009 season brought inconsistency, as they took 4th place in the regional league but knocked Urawa Red Diamonds out of the Emperor's Cup in the second round, their biggest giant-killing ever.

In 2011, despite a season thrown off by the Tōhoku earthquake and tsunami and the resulting inability of Sony Sendai to play a full schedule, Yamaga earned 4th place and were promoted to J.

The mascot of the club is named "Gans-kun" (ガンズくん), who is a Ptarmigan (ターミガン, Tāmigan), the symbol bird of Nagano Prefecture.

[citation needed] On 23 November 2016, Matsumoto Yamaga and Geylang International signed a Memorandum of Understanding (MOU) in a press event which was held at the Marina Bay Floating Platform.

The MOU spells out possible areas of collaboration such as the exchange of players and technical staff for training attachments and loans.

Amongst the key initiatives of the partnership with Matsumoto Yamaga is the exchange programmes for head coach, Mohd Noor Ali, who had a one-year attachment with the club in 2018, where he guided the club U18 B team to the Japan FA's Under-18 Football League Nagano prefecture title while on 17 August 2018, Anders Aplin become the first Singaporean football player to sign for a J.League team signing on loan until the end of the 2018 J2 League season in November.

On 30 October 2022, both clubs reaffirmed their close and long-standing relationship as Geylang International officials went to Japan to explore future collaborations going into the seventh year of partnership since 2016.