What this record means
The record shows that FUN is a live Principal Register registration (Reg. No. 2220871) owned by Fuji Seimitsu Co., Ltd., a corporation organized in Japan, and it has been renewed as of February 13 2019. The registration covers only one class—Class 006—with the listed goods “Nuts made of metal,” first used in commerce in March 1997; therefore, a later use of the word FUN for metal hardware or similar fasteners would be the closest record‑based concern, while uses in unrelated fields such as software, food, or apparel fall farther from the scope shown. The record does not give Fuji Seimitsu control over every possible use of the word FUN, just the specific metal‑nut goods listed. The prosecution history shows the normal filing, publication, allowance and registration sequence, ending with routine Section 8/9 renewals; there are no oppositions, cancellations or other enforcement actions noted. I'd treat this as a meaningful concern if you plan to market metal fasteners under a similar name.
Informational only - not legal advice.