Would like to share a IJN Type 4 Grenade 四式陶製手榴弾 (Pot grenade/Ceramic grenade) which I acquired in Japan last year.
I've seen quite a few examples, but this one is rather interesting.
The light flat brown color and the maker stamp. Circle with the Kanji 富(Tomi) Wealth in English.
The full name of the company is 国富産業有限会社 Kunitomi Sangyou Yuugen Kaisha (KTT Tech). This company still present.
It is hard to find a Type 4 Grenade with maker mark on.