Unlike the English writing system (which is composed entirely of the 26 letters of our alphabet), the Japanese writing system consists of three groups of characters which are primarily syllabic. This feature can lead to the creation of some fun mnemonics. The following are a few of my personal mnemonic ideas for characters from the hiragana group. They have been effective in helping me commit the sound and character sets to memory, and I hope these can inspire you to create some of your own as well.
Shi. This resembles the shape of a hook, much like a mirrored J. One purpose of a hook is to catch fish, and so I relate this to the the expression that tells others to be quiet in order to avoid scaring away the prospective fish: “Shhh…“
Tsu. Tsunamis can be powerfully devastating forces of nature. Tsu is a curved character that could easily be the outline of a fingertip directed east. This curve also seems to mimic an ocean wave racing towards the shore. For greater emphasis, one can imagine an observer who is so overwhelmed by the sight of a giant wave that he can only stutter and point, unable to finish the complete word: “Tsu…tsu-tsu!“
To. While the previously mentioned characters require only a single, curved stroke, this one uses two. The first is a short, straight line that imagine to be a sharp object such as a splinter or nail. It seems to stab downwards into the second stroke – a curve that resembles the outline of a “toe” pointed west.
No. This reminds me of an incomplete no symbol (the red circle with a line drawn across its diameter). If you skew the symbol a few degrees and leave a bit of the circle unfinished (open space) on the right side of the line, you get something that would appear more like the character.
Ko. This might not be too helpful because it involves the application of a Chinese word: “kou.” It sounds similar and means mouth. I envision the first, smaller horizontal stroke as an upper lip, and the second longer horizontal stroke as a lower lip.
These are only a few out of many, and what works for some may not work for others. However, these are simply to serve as examples or ideas to help you come up with our own fun ways of remembering characters in the Japanese writing system.