Nobody

The name on the nakago is 兼氏 - Kaneuji.

The last character may be 左 (sa/hidari) - left.

“岩船郡八幡村大字八□□ – Iwafune-gun, Yawata-mura, Oaza …” is an old address, and the details are unknown. The address is now included in the following area. Ref. Sanpoku, Niigata - Wikipedia Tohashi – family name Hisajiro - first name I am sure he is no longer living. I do not think that sending it back to Japan is a good idea, unless the blade is national treasure level.

岩船郡八幡村大字八□□ – Iwafune-gun, Yawata-mura, Oaza … 富樫久治郎 – Togashi Hisajiro

紙和鋼安来以吉久作之 – From 紙和鋼 of Yasuki/Yasugi, Yoshihisa made this. I am not sure about the correct reading of 紙和鋼. “和鋼 (wako)” might be another general name of Tamahagane. Ref. 和鋼 - Wikipedia

天明六丙午歳初春 – Tenmei 6 Hinoe-Uma year (1786), early spring 源應擧寫 – Minamoto Okyo’s painting Ref. Maruyama Ōkyo - Wikipedia

I guess that 山本淸 (Yamamoto Kiyoshi, 1883-1960) is the Yamamoto Gonbe’s oldest son. Yamamoto Kiyoshi was a naval officer, politician, and nobility. His father Yamamoto Gonbe (山本権兵衛) was an admiral of the Navy. Ref. 山本清 (海軍軍人) - Wikipedia Ref. Yamamoto Gonnohyōe - Wikipedia Yamamoto Kiyoshi was living in Shiba-ku, Takanawadai-machi in early Showa period. I guess that the card was used before or during WWII. The first three characters of the handwriting might be 外務省 (the Foreign Ministry).

I think that the number written over nine is eight.

The sword is a Chinese reproduction. 中國大連陳朝波 – China Dalian, Chen Chao-Po 辛己年 – Year of the Snake (2001) Ref. Paul Chen sword inscriptions - Auctions and Online Sales or Sellers - Nihonto Message Board

He died in the Battle of Ichi-no-Tani.[5][6] His body was identified by a signed poem that was fastened to his quiver. The poem read:[4]: 96  Evening drawing on, I'll take lodging in the shade of this tree, and make its blossoms my host for the night. Ref. Taira no Tadanori - Wikipedia

Its mei is 関兼延 - Seki Kanenobu.

I read the kanji as follows, 拾圓本　　　　日可□　　　　國 銀禾和　　　　錢五東　　　　戰 However, I cannot understand the phrases. They might be Chinese words.

I cannot see the context. Please show us the all characters in one picture.

備前介宗次 - Bizen no suke Munetsugu

It is a writing mistake. 昭和十七年 - Showa 17th year (1942). 正和 (Showa) period = 1312-1317

The tag shows the original owner's name and address. 大阪市西成区潮路通一□七 - Osaka-shi, Nishinariku, Shiojidori 1?7 小林直太郎 - Kobayashi Naotaro

Is there another kanji overwritten by 次? It might be 宗.

清心子正行 – Seishinshi Masayuki 慶應二二年八月日 – Keio 4th year (1868), 8th month

井上真改 - Inoue Shinkai

Maybe, 江戸神田住 - Edo Kanda ju 政方 - Masakata

As a guesswork, Hyoshigi ( wooden clappers) Ref. Hyōshigi - Wikipedia 日本刀販売専門店　銀座長州屋　鍔　鐔　販売品　拍子木透鐔　無銘　古金工, 鍔, 古金工

I believe that the name and address were written by its original owner during WWII. And other writings look like the same handwriting. He had his own philosophy.

The paper says late Muromachi.

Late Edo period 行年七十一才 – 71 years old 埋忠家寿 – Umatada Ietoshi

These may be some life lessons. 水ハ苦クシテ求メヨ – Make the water bitter and drink it. 人ト人間ノ差 – The difference between a man and a human The first part of this sentence is unclear. 波…ハ世ノ 常デ……………… 任セテ雑魚ハ 歌ヒ雑魚ハ オドル サレド 誰ガ知ロウ 百尺下ノ 水ノ心ヲ 水ノ深サヲ However, I know that this sentence is the last part of a novel “Miyamoto Musashi” written by Yoshikawa Eiji. The whole sentence must be like this. 波騒は世の常である　波に任せて泳ぎ上手に　雑魚は歌い　雑魚は踊る けれど誰が知ろう　百尺下の水の心を水の深さを - Waves and noises are the norm in the world. Let the waves go, swim well, the small fish sing, and the small fish dance. But who knows the heart and the depth of the water a hundred feet below.