Torneko's shop is in the town of Endor, south of the church and to the left of the inn. It is owned by Torneko Taloon in Dragon Quest IV.
In Chapter 2, an old man in the southwest corner of the town hoped to sell his shop to one who is interested in running a business.
In Chapter 3, he found a buyer in the form of Torneko Taloon after the former prevented a fued between Endor and Ballymoral Castle. The old man sold his shop for 35,000 gold coins, and thus Torneko and his family (his wife Tessie and son Tipper) moved in. Tessie herself ran the shop while Torneko found various items/weapons/armours/shields/helmets to sell.
In Chapter 5 & Chapter 6, Torneko traveled around the world to find various treasures, as well as aiding The Hero and company in defeating Estark The Lord of the Underworld (and later Psaro the Manslayer, then Aamon). As a result, Tessie converted the shop into a bank (vault in the NES Version).
Equipment selling prices
Whenever given a piece of equipment, Tessie sells them for a higher amount of gold than other stores would sell them for.