Passolo letters count algorithm

To whom it may concern.

I would like to know the algorithm about statistics of Passolo.
I checked a description about letters on the help. But it doesn't descripbe about Japanese and Chinese character.

Letters The number of letters, e.g. a , Z , é

 

I checked the following stirngs. 
Count of Letters in Chinese makes sense.
But Japanese ones don't make sense.
If Passolo counts only alphabet and Kanji character as Letters, it accounts for the fact.
Is it possible to give me more detail about it?

和或其 ABC 供应商的其它知识产权
Description Strings Words Letters Characters
Total 1 3 16 18
サプライヤー ABC のその他の知的財産
Description Strings Words Letters Characters
Total 1 3 8 20
Windows 10 是个人电脑的操作系统。
Description Strings Words Letters Characters
Total 1 2 17 22
Windows 10 はパソコンの OS です。
Description Strings Words Letters Characters
Total 1 2 9 24