From ''Kyoukai Senki'' by Bandai comes the HG Bunyip Boomerang! It can replicate its three states, such as the patrol state, the high mobility combat state, and stationary state via the replacement of parts. The head unit can be stored away and the machine gun and hidden knife can be deployed with the use of parts, as well.
Knife parts (left and right)
Self-supporting auxiliary parts x2