More than 20,000 documents of the Inoue Sekiemon family business have survived, including matchlock firearm orders, deliveries, and payments. These records provide a complete picture of the matchlock business in the Edo period (17th to 19th century).

Sakai gunsmiths were engaged in the custom manufacture and sale of matchlock firearms both to feudal lords throughout Japan and also　to farmers for threatening and driving away animals damaging crops. In 1842, they had business relationships with 239 feudal lords and equivalents (over 80% of the total).

The Inoue Sekiemon family had 19 longstanding customers in 1758 and 20 in 1801. By 1842 the number had expanded to 61, more than any other gunsmith in Sakai.

These customers were located mainly along the Seto Inland Sea and in the north Kanto region. In 1842, 40 out of 61 were minor feudal lords charged with supervising military equipment at Osaka Castle. In addition to from the Ozu domain, the family also came to receive pay from Iyo Yoshida domain. Over time, the family expanded its sales channels, all the while strengthening relationships with longstanding customers.