Japan, Pattern or medal? Meiji era. [solved]

Hi, does anyone have a clue what this is?

Diameter 31.8-31.9mm

Thickness 1.7mm

Mass 2.7(3) grams

Composition Aluminium

It looks a lot like the pattern of ¼ Yen - 1Yen 1870 but I found no evidence of existing Aluminium patterns.

N#402984

or

N#402983

Aluminium was quite expensive around 1870, so probably not just a token.

Or is it a medal? But for what occasion? A mistery for me.

 Both faces show the same design.

Definitely it is not a forgery sold on Temu. 

Kind regards

https://www.britishmuseum.org/collection/object/C_1914-0107-49 

Object Type - coin - proof
Museum number - 1914,0107.49
Description - Aluminium 50 sen or 10 yen trial coin. 
Sunburst surrounded by alternating chrysanthemums and paulonia. (obverse)(reverse)
Production place - Asia: Japan
Materials - aluminium
Dimensions - Diameter: 32 millimetres
Weight: 2.98 grammes
Curator's comments - 
Joe Cribb: "This piece has the design used by the Royal Mint to trial a Japanese 

coinage when negotiating to sell the Hong Kong mint to Osaka. 

The Royal Mint has a set of dies and a set of strikings taken from them. I have seen another set in the UK."
五十銭型 (五十銭型アルミ素材見本？) (identified by Shinichi Sakuraki)
Location - Not on display
Acquisition name - From: Dr John Brighouse
Acquisition date - 1914 

Thank you so much ZakUK!