さ

Imagine there’s a samurai sword with a silly bent end. This character is spelled “sa” like the first two letters of “samurai”.

し

This character looks like a woman’s long hair, curled at the end. It sounds like "she".

す

This character looks like a sprouting seed that will soon be a plant. It’s spelled “su” and sounds like the “soo” in “soon”.

せ

Imagine that the horizontal line is the horizon, and that the sun is setting. This character is spelled “se”, like the beginning of “setting”.

そ

This looks like a zig-zag sewing stitch. It’s spelled “so” and sounds like “sew”.