ツ(tsu)・シ(shi)・ソ(so)・ン(n)
Almost everyone, even sometimes Japanese people have trouble with these.
There are 3 basic differences:
- #of ‘dashes’
- Direction of dashes
- “ノ” part stroke direction
シ(shi) and ン (n) form the horizontal pair. し～ん (the ‘sound’ for silence, may help you to remember this). They have horizontal dashes and their line starts from the bottom.
ツ(tsu) and ソ (so) form the vertical pair. They have vertical dashes and their line starts from the top.
Although I said vertical and horizontal, its a degree of slant issue. Horizontal and vertical are just easier to visualize and remember than “slightly more slanted”
All you need to remember is the direction of the dashes. If you write the dashes correctly, you can go to the part of the ノ that is closest to you. That is to say, if you drew vertical dashes from left to right, you are closer to the top right than the bottom left.
If you drew horizontal dashes from top to bottom, you are closer to the bottom left than the top right.
Distinguishing these kana quickly will take a while. Context will be your biggest ally, but if you aren’t sure look at the dash direction.
し～ん = Silence (an equals sign is 2 horizontal lines).
A tsunami is vertical.
Good luck.
シ(shi) and ン (n)
Horizontal dashes
line starts from the bottom.
ツ(tsu) and ソ (so)
Vertical dashes
Line starts from the top
I made a quiz for this, here.