Nobody

5th, 第八十五警備隊 –The 85th Guard Unit 海軍大尉吉田雅維 – Navy Lieutenant Yoshida Masayuki/Masatada (reading?)

Maybe 丸山部隊 (Maruyama unit/corps/force...)

後藤光寿 - Goto Mitsutoshi

カワサキ - Kawasaki

緑水 (ryokusui) - green water

安藤兼基作之 - Ando Kanemoto made this.

安次 (Yasutsugu) or 安元 (Yasumoto) ???

I might have the same thought as you have. As a wild guess, 二王清助作 - Niou Kiyosuke saku (?????)

FYI, there is another Kawachi no kami Fujiwara Msahiro. Ref. Masahiro 2nd 【脇差】 河内守藤原正広――倉敷刀剣美術館 (touken-sato.com)

中號 – Medium size 昭和十八年製 – Made in Showa 18th year (1943) 本廠檢定 – Approved by the Head (Army Clothing) Depot 行田納 – Supplied by a factory in Gyoda (I’m unsure.)

兼波作 - Kanenami saku

Might be 大嶋 - Oshima

The flipped image looks upside-down. Here is a rotated image.

包矩 - Kanenori

or 家武 - Ietake

伊与住 - Iyo ju 正阿弥家正 - Shoami Iemasa (unsure about the last kanji)

The third tsuba, 八幡太郎鳩丸 – Hachiman Taro Hatomaru 御太刀鍔 – On-Tachi tsuba (tsuba for a tachi)

OK, let's agree to disagree. I simply think that there are little bases to say something.

You might misunderstand another point. Mitsuhashi is one of families uses the mon (丸に三文字). But it does not mean that all Mitsuhashi families use the same mon. According to the linked page, a representative mon used by Mitsuhashi family is 兎紋 (Usagi-mon). Ref. 【兎】兎紋一覧（うさぎ）：家紋のいろは (irohakamon.com) Family crests and family names are many-to-many relationships. We do not know the mon Mitsuhashi Toranosuke used.

As far as I know, 1. The mon is used MANY families. And most of them do not have “三” in their family names. Mitsuhashi family is only one of them. 2. As I said before, I do not think that Mitsutachibana is a family name. 3. I do not know why Hawley write 三橘 there. Only a typo? IMO, I do not understand why we must stick to Mitsuhashi name in this situation.

三橘 (Mitsutachibana) is an improbable family name. But there is a family crest whose name is Mitsutachibana. Ref. 三つ橘紋（みつたちばな）：家紋のいろは (irohakamon.com)

関住不破兼若作 – Seki ju Fuwa Kanewaka saku And you should take clear pictures for its date.

This is only my guess. 君命重夳(=泰)山 – The order of my load is heavy as Mount Tai.

Frankly, I have doubts about your theory. Just to confirm, the second picture is saying that the crest is used by Fujikake and Mitsuhashi families? I found that the crest is used by more than 50 families. BTW, 三橘 does not read Mitsuhashi but Mitsutachibana. Ref. 丸に三文字紋（まるにさんもじ）：家紋のいろは (irohakamon.com) Is the mark in the first picture really a family crest? That might be a trademark of a shop or mere memo. Trademarks and family crests are different. I do not think that a shop owner uses his private family crest as the shop’s trademark. The mark in the first picture and the crest in the second picture look different to me. Therefore, there is no evidence that Mitsuhashi Toranosuke has something to do with the mark or the gunto you have.

My guess, That is an auction market regularly held mainly by dealers.