Chogokin

Chogokin is probably the older and most famous Japanese action figure series, which is tightly associated with everything metallic and robotic. Indeed, the term chogokin originally came from Mazinger Z, a manga by Go Nagai, to design a fictitious metal alloy used to build robots. It was first used from 1974 to 1987 as an action figure series name by Popy, a subsidiary of Bandai, which disappeared since because of general lost of interest in mecha / robots at the time.

Since 1997, Bandai has applied the name to several action figure series that all have in common to use die-cast metal as the material of choice to represent robots or metallic characters. The main series are the following:
 * Chogokin 超合金, the original series that Bandai rejuvenated in September 2005 with scarce releases.
 * Soul of Chogokin 超合金魂, the current main series since 1997. Each figure, mainly taken from old 70s and 80s series, is of high quality, big size (20 to 50 cm) and very expensive.
 * DX Chogokin DX超合金, also started in 1997. It was about robots of more recent Japanese series but has shifted since late 2008 to be exclusively focused on Macross Frontier.
 * Soul Spec 魂SPEC, short name for Soul of Chogokin Spec. Since early 2007, this series feature is to release robots as metallic skeletons (enabling to see their internal parts), on which some plastic parts can be attached to form their external armor.
 * Super Robot Chogokin スーパーロボット超合金, with a first figure released mid-2010. With sizes of around 14 cm, mid-price range but still high quality, figures of this series have been created to target the market occupied by Kaiyodo's Revoltech.

In parallel to the main series, Bandai also created several derivative series:
 * S.I.C. for Super Imaginative Chogokin, is an action figure series that started late 1998, completely focused on metal hero characters. It has spawned 2 other budget series: S.I.C. Takumi Damashii (S.I.C. 匠魂, figures around ¥500 since mid-2003) and S.I.C. Kiwami Tamashii (S.I.C. 極魂, figures around ¥1,500 since early 2009). S.H. Figuarts is the all plastic equivalent series.
 * Souchaku Henshin 装着変身, literally Armor Transformation, S.H. in short. Series created in 2000, it was focused on metal hero characters (from live-action series like Kamen Rider) as action figures and their removable armors. It has been succeeded by S.H. Figuarts since early 2008, which completely departed from the chogokin trademark.
 * Otona no Chogokin 大人の超合金, literally Chogokin for Adults, is a series that started early 2010 with very sporadic and pricey releases of realistic reproduction of current spatial machinery.

Chogokin Franky
This is an action figure made of die-cast metal with accessories and interchangeable body parts, representing Frankythe cyborg.
 * Release date: late December 2011
 * Price: ¥9,975, VAT included
 * Size: 19 cm tall

Chogokin Going Merry

 * Release date: late June 2012
 * Price: ¥13,440 (VAT included)
 * Size: 28 cm long

Highly customizable Going Merry, coming with 2 life boats, a Klabautermann, and 11 mini-figures of the Straw Hat at the time of Going Merry's funeral, Kokoro, Chimney and Gonbe.

The first production release also came with an octopus balloon as a bonus.

Chogokin Franky Tank Option Set
This set is an addendum to the original Franky release, i.e. it only contains a tank base and a few accessories.
 * Release date: August 2012
 * Price: ¥4,200 (VAT included)
 * Size: 8 cm tall

Reference

 * History of Chogokin on Figure Maniax (French)