I really wish it was that simple.
"Is there any plural in Japanese?
It’s very hard to answer this question. Normally, Japanese native speakers do not differentiate the plural nouns from the singular. In other words, the border is very, very ambiguous. This fact would be surprising and perhaps confusing to Japanese learners, especially those who are familiar with the language which has a clear border. But, unfortunately, this is the trait of the Japanese language and how Japanese native speakers use nouns"
[...]
"Sometimes Japanese people use the suffix, “tachi”, to make the plural form of a noun. Its pronunciation can be a voiced sound depending on the noun used together with it. This method can be applied to “tomo” to make its plural form “tomodachi”. Grammatically, therefore, “tomodachi” is a plural noun. But Japanese people started using it also as a singular, so this word can work in both ways. Sadly, the border became ambiguous again."
https://japaneseparticlesmaster.xyz/plural-in-japanese/ 
