Grandpa Singing

Song for small kids.
Grandpa(s) and grandkid(s) can enjoy it together.
Much more fun if they sing along to the latter verse of each section. For the final chorus, everyone can join in, including grandma(s), dad(s)/mom(s) and nursery school/kindergarten teachers!

Its Japanese lyrics is described in English as follows (just an interpretation, not in the lyric style).
<#1
An old man was singing alone, sounding lonely.
A friendly old man came over and that all sang happily.>

<#2
The old man next door came over and complained about how loud the singing was.
But when they all sang together, it was fun and all laughed.>

<#3
An angry old man came over and kept complaining about something.
But when they all sang together, it was fun and all laughed.>

<#4
An old man who looked depressed came over, saying "I was so tired".
But when they all sang together, it was fun and all laughed.>

<Chorus
A lot of old men came over and they all sang together with smiles on their faces.
Singing together is fun, it's happy, it's fun.
It's happy, it's fun.>