Smartphones launched by the top-three Japan-based telecom operators for summer 2015 are almost identical in hardware specifications, but the carriers have been trying to differentiate their products with special features, according to Digitimes Research.

The three carriers, NTT DoCoMo, Softbank and KDDI au, all are selling smartphones from Sony Mobile Communications and Samsung Electronics, blurring the brand recognition.

Four out of the eight models released by NTT DoCoMo feature biometrics authentication capability, including Fujitsu's Arrow NX F-04G with iris system, Samsung's Galaxy S6 and Edge S6 with fingerprint recognition, and Sharp's Aquos Zeta.

Softbank is offering a waterproof model, the Aquos Crystal 2, from Sharp, while KDDI is rolling the Isai Vivid based on LG G4 as well as the Torque G02, a sea water resistant smartphone from Kyocera.