It is an angular block mug, so why are the inside of the cup and the handle rounded?

Maruhiro's block mug has a neat block shape on the outside, but there are no angular corners on the bottom inside the cup^[1]. Because the corners are rounded, sponges sweep through the entire bottom without catching when washing dishes, preventing beverage residue from drying up in crevices.

The areas that touch hands and lips have also been neatly rounded. The inside of the handle and the rim of the cup are smoothly curved, providing a soft touch when drinking beverages or holding the cup^[2]. The lower part of the handle is shaved at an oblique angle to provide stability when gripped by hand, and the inside where fingers touch is rounded to relieve the strain placed on the hand^[3].

hmmm, while preserving the neat block contour of its exterior appearance, the parts that come in contact with the body have been smoothly rounded, ensuring the comfort of an everyday tool you naturally reach for.