Name is missing even though name exists

This is the site I guess https://www.openstreetmap.org/way/193446505#map=19/42.85911/140.70727
I don't edit much in countries apart from my own, Australia, but I would guess that it is because name=雪山 or name=Nichigo Apartments needs to be added depending on which name you prefer to show on the Standard map at openstreetmap.org
I think that you would normally be expected to use the local language version which in this case would be name=雪山
I expect that name:en=Nichigo Apartments and name:ja=雪山 are there for other map providers to give more choice with which language they wish to display.
I am not familiar with all the nuances with language so someone with more knowledge is likely to add more info for you.

nevws answer is in principle correct.

It is common practice in OSM to add the name in the script and language of the country/region in question to the name field. Any commonly in use non-local language versions (not translations!) to name:xx The standard map style will only use the name attribute and none of the other language variants.

It becomes tricky in multi-lingual areas however that is out of scope for this question.

Besides the above you need to tell us which editor you are using, because that is likely where the error message is coming from.

PS: please add comments as comments and not as answers