Biwako Shiga

The club was formed in 2005 from the former Sagawa Express SC Kyoto. They were first called Mi-O Biwako Kusatsu. In 2007, upon promotion to the JFL, they renamed themselves simply MIO Biwako Kusatsu until 2011.

Regional League and promotion to JFL (–2007)

In 2007, MIO Biwako Kusatsu secured third place in the regional playoffs of the regional playoffs, earning promotion to the JFL for the 2008 season. This marked their first promotion to the Japan Football League at the end of 2007.

JFL (2008–2025)

MIO Biwako Kusatsu played their first season in 2008 where they finished 14th.

In 2012, they renamed themselves as MIO Biwako Shiga, in order to extend their fanbase to the entire extent of Shiga Prefecture, particularly the area around southern Lake Biwa, in where they mostly have played matches.

In 2022, MIO Biwako Shiga finished in the last place out of the 16 participating teams in the season. The club, however, was not relegated back to the Kansai League, as JFL's top 2 teams were promoted to the J3. Under the league system, MIO Biwako would only be relegated as the last-placed team if no team or only one team had earned promotion to the J3 during the season, which was not the case.

On 27 January 2023, MIO Biwako Shiga announced a name change, becoming Reilac Shiga. On 1 February, the new identity was fully introduced with the crest release.

J.League (2026–present)

In 2025, they ended in 2nd place, four points behind the champions Honda FC and qualified for the Promotion-Relegation play-offs against the bottom-placed 2025 J3 League, Azul Claro Numazu. On 14 December, Reilac Shiga secure promotion to the J3 League for the first time in their history, after winning 4–3 on aggregate.