Identification help needed - Japanese Katana

I found this in my father-in-law's attic after his death this summer. He did not serve in the military and his brother that was in WW2 was only in Europe. His father did operate a gun repair shop in the 50s & 60s.

This had been the family home since 1960 and this was buried at the very back under the eaves, so I suspect it has been there approximately 50 years.

The sheath is plain wood, lightly stained.

I've attached multiple photos of the blade, hopefully that will provide enough detail for identification.

I appreciate any help that can be provided.

thanks,

Mark

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entire_blade.jpg422.88 KB
mkj_sword_006_r.jpg1.85 MB
mkj_sword_007_r.jpg1.77 MB
mkj_sword_008_r.jpg1.94 MB
mkj_sword_009_r.jpg1.53 MB
mkj_sword_010_r.jpg1.25 MB
mkj_sword_011_r.jpg1.3 MB
mkj_sword_012_r.jpg1.2 MB
sword_point_r.jpg332.68 KB
tang_side_a_r.jpg212.87 KB
tang_side_a_upper_detail_r.jpg842.86 KB
tang_side_a_lower_detail_r.jpg926.87 KB
tang_side_b.jpg1.79 MB
tang_side_b_upper_detail_r.jpg1.11 MB
tang_side_b_lower_detail_r.jpg1003.94 KB

Hi Mark, It looks like a

Hi Mark,

It looks like a genuine war-time Japanese sword in civilian mounts (originally).

The signature reads:

東都住源?國
tōto ju minamoto ? kuni
昭和ニ十年ニ月日
showa 20 nen 2 gatsu hi

(Showa 20 (1945), February)

I'm not sure how to read the ? character (the first character in swordsmith's name, kuni).

Regards,
Stan

Stan, Thank you for the

Stan, Thank you for the identification. I'm not going to try to clean it up since I'm concerned I would screw it up. Anything I should do to it to prevent further deterioration? Any idea of valuation for insurance or is it not worth the expense of covering it?

thanks,

Mark