This tiny basic smartphone runs Android 4.2 Jelly Bean (yes that is the pre-KitKat Android, no mistake here!) and is powered by the MediaTek MT6752A processor. Priced around US$90, it is scheduled to hit Japan later this week.
https://www.notebookcheck.net/Credit-card-sized-NichePhone-S-handset-debuts-in-Japan.262690.0.html