This is the multi-purpose Type 88 Instantaneous impact type artillery fuze with its safety wire and shipping can. 

Not to be confused with the "Small Type 88"  fuze typically used with the 50mm "Knee Mortar".
 

Here are two differnt marking schemes for this fuze.

At left are three Kanji symbols
Read top to bottom:
"Field" "Mountain" "Cannon". 
 

An alternate marking scheme, shown right, has the "88 Type" designation as well.

This fuze was used on antitank, tank, field artillery and howitzer ammunition.

Sometimes mortar rounds will appear with this fuze attached. While the term "Gun and Howitzer-Mortar" is used to describe this fuze in U.S. identification manuals, it requires centrifugal force (spin) to arm it, which a mortar does not provide.

U.S. TM9-1985-5 indicates this was made in two types, with differences in the strength of the internal latch spring safety inside, but outwardly identical. A strong spring version for gun use and a weaker spring (less set-back force requires) for howitzer use. It would seem, if this were true, there would be markings on the fuze to identify the types. 
I personally think this is incorrect and there is only the one design and it was not used on mortars.

Fuze bodies were also made of blackened steel.