Help in identifying grass

I live in Japan. Does anyone know the name of this grass? It’s kind of like long wavy hair. Grows in a tuft. I’ve seen similar in Japanese gardens. Thanks!

That looks like mondo grass to me.

Ophiopogon_japonicus

I think you're probably right. It looks very like a black ornamental grass that is planted in the UK


source

Apparently it is not botanically a grass, but has berries, so you could wait for it to fruit to confirm the ID.

That’s it! I even saw the blue berries. Thank you.