All weapons used by the LDF are known to be used/taken from JSDF stockpiles as "donated" by local governments to defend libraries against the Media Betterment Act (MBA).
Minebea P9
The main sidearm of the LDF is the Minebea P9, a licensed copy of the SIG-Sauer P220 manufactured by Minebea and Shin Chuo Kogo KK. Kasahara (Nana Eikura) and Captain Genda (Jun Hashimoto) wield these weapons. Various LDF soldiers are seen with the P9 in their holsters.
Minebea M-9
The primary submachine gun of the LDF is the Minebea M-9, a copy of the Mini Uzi manufactured under license by Minebea.
Mini Uzi
For some reason, not enough PM-9s were available for the LDF extras during production. The Mini Uzi was used as a stand in for the Minebea M9, due to the latter being based on the Mini Uzi. The folding stock appears to have been removed
Howa Type 64
The Howa Type 64 is used as a training rifle for all recruits prior to indoctrination into the LDF, most noticeably Tezuka (Sota Fukushi) and Kasahara
Special Behind The Scenes
Howa Type 89
The Howa Type 89 is the main assault rifle of the LDF.
Dojo throws an M84 stun grenade into a room during a hostage rescue. It's surprising that the LDF never employ stun grenades during their battles with the MBC, despite not shooting to kill.
Media Betterment Committee
Heckler & Koch MP5A4
The standard submachine gun of the MBC is the Heckler & Koch MP5A4. These weapons are occasionally seen outfitted with Surefire 628 forearms and, on one occasion, sound suppressors attached to the muzzle.
Bakushukai Militants
Norinco Type 56
At least one Bakushukai Militant is seen wielding a Norinco Type 56 in the film's intro.
M2 Flamethrower
One of the Bakushukai Militants uses an M2 Flamethrower to burn down the Hino Library.