Kinkan 金柑 - The Gold Citrus

Biwa is a Japanese musical instrument and a famous lake in Japan, having the shape of the musical instrument. Biwa is also a fruit - Eriobotrya japonica, loquat. It has a very thin skin and can be easily peeled off when the fruit is ripe. 

A similar fruit is kinkan  - 金柑 "gold" and "citrus" - known as kumquat. Kinkan - Fortunella japonica or Citrus japonica - looks like a very small orange.

Even though loquat and kumquat are botanically unrelated, their names both originate in the same Cantonese word.

Photos of kinkan:

The length of this fruit is maximum 5cm.

While taking photos of the fruit in a garden, the owner noticed me and offered some.