What origin is the " Kobashigawa " surname and its legacy or history,?

Surnames in themselves do not have a family history. A person's ancestors with a surname have the history. I don't know about Japan but in Europe when people took surnames during the last millennium it wasn't to identify a man as a member of a family but just to better identify him, frequently for taxation purposes. Too many men named John, Joseph, William in the same town or village and they had to have a way of sorting them out on records. When they got through it wasn't impossible for legitimate sons of the same man to wind up with a different surname and still each could have shared his with others with no known relationship.

There are surname product peddlers who like to make you think they do so you will buy their product. They sell things like surname history scrolls and family coats of arms. They frequently use the misnomer "family crest" which is a small part of a coat of arms. Coats of arms were/are granted to individual men, not families and definitely have nothing to do with surnames. A good way to tell that a coat of arms a person has displayed was bought from one of the scam merchants is it will have a surname on a scroll underneath and sometimes over it. Coats of arms that have been validly granted (and sometimes assumed in continental European countries) will not have a surname anywhere attached.

It's Japanese. There are a number of people with that name in Hawaii. They all have a story. The stories, legacies and histories will be different for each family. If they are typical, the first generation came to Hawaii as low-paid laborers, worked hard, valued education, had a son who served in the 442nd, who, if he lived, came home with a Purple Heart and some other medals, and the third and fourth generations are now optometrists or CPAs or shop keepers.

A word which a surname is is nothing to do with ancestry, so it has no connected "legacy or history" so if you wish to know anything about your ancestors you need to research the people who just happened to choose and use that word as a name.... if you wish to know word history then that is language and called etymology ( word history) but that will tell you zero about ancestry

Sounds Japanese