I am happy to know that foreign people who are interested in Mikasa exist.
Although my writing speed is very slow, I will provide information about Mikasa as far as I know.
I consider that Mikasa's armament at Tshushima (1905) was below.
[Mikasa at Sasebo, Feb., 1905. (click the image to enlarge)]
(1), (2) 12 inch gun
(3) 6 inch quick firing gun #1
(4) 6 inch quick firing gun #3
(5) 6 inch quick firing gun #5
(6) 6 inch quick firing gun #7
(7) 6 inch quick firing gun #9
(8) 6 inch quick firing gun #11
(9) 6 inch quick firing gun #13
(10) 12 pounder(76 mm, 3 inch) quick firing gun #1 (on central pivot mounting, with shield) in crew space.
(11) 12 pounder(76 mm, 3 inch) quick firing gun #3 (on pedestal mounting, without shield) on fore shelter deck.
(12) 12 pounder(76 mm, 3 inch) quick firing gun #5 (on pedestal mounting, without shield) on boat deck.
(3) 6 inch quick firing gun #1
(4) 6 inch quick firing gun #3
(5) 6 inch quick firing gun #5
(6) 6 inch quick firing gun #7
(7) 6 inch quick firing gun #9
(8) 6 inch quick firing gun #11
(9) 6 inch quick firing gun #13
(10) 12 pounder(76 mm, 3 inch) quick firing gun #1 (on central pivot mounting, with shield) in crew space.
(11) 12 pounder(76 mm, 3 inch) quick firing gun #3 (on pedestal mounting, without shield) on fore shelter deck.
(12) 12 pounder(76 mm, 3 inch) quick firing gun #5 (on pedestal mounting, without shield) on boat deck.
(13) 12 pounder(76 mm, 3 inch) quick firing gun #7 (on central pivot mounting, with shield) on upper deck.
(14) 12 pounder(76 mm, 3 inch) quick firing gun #9 (on central pivot mounting, with shield) on upper deck.
(15) 12 pounder(76 mm, 3 inch) quick firing gun #11 (on central pivot mounting, with shield) on upper deck.
(16) 12 pounder(76 mm, 3 inch) quick firing gun #13 (on central pivot mounting, with shield) on upper deck.
(17) 12 pounder(76 mm, 3 inch) quick firing gun #15 (on pedestal mounting, without shield) on boat deck.
(18) 12 pounder(76 mm, 3 inch) quick firing gun #17 (on pedestal mounting, without shield) on aft shelter deck.
(19) 12 pounder(76 mm, 3 inch) quick firing gun #19 (on central pivot mounting, with shield) in admiral's saloon.
(20) 3 pounder(47 mm) Yamanouchi(*1) heavy quick firing gun #1 on fore shelter deck.
(21) 3 pounder(47 mm) Yamanouchi heavy quick firing gun #3 on boat deck.
(22) 3 pounder(47 mm) Yamanouchi heavy quick firing gun #5 on boat deck.
(23) 3 pounder(47 mm) Yamanouchi heavy quick firing gun #7 on aft shelter deck.
(24) 2.5 pounder(47 mm) Yamanouch light quick firing gun #1 (on pedestal mounting) on fore bridge deck.
(25) 2.5 pounder(47 mm) Yamanouch light quick firing gun #3 (on pedestal mounting) on aft bridge deck.
*1 "Masuji Yamanouch" (Imperial Japanese Navy officer (1860-1919)) who improved existing (maybe "Hotchikiss") quick firing gun.
According to the log of Mikasa, on 29th(and 30th), Dec. 1904, eight 47mm Yamanouchi heavy quick firing guns on the fighting tops were removed and relocated to the shelter decks or the boat decks. Previous to this relocation, four 47mm Yamanouchi light guns on the boat decks were relocated to the bridge decks.
(a), (b) Fighting tops were removed after the battle of Yellow Sea (1904).
(c), (d) Officer's conning(?) towers were fitted with on four casemates on upper deck January, 1905.
* * * * *
Mikasa's armament was : 4 x 12 inch guns, 14 x 6 inch guns, 20 x 12 pdr (3 inch) guns, 8 x 3pdr (47 mm) guns, 4 x 2.5pdr (47 mm) guns and 4 x 18 inch submerged torpedo tubes.
Note: One Japanese claims that two 2.5pdr (47 mm) guns relocated in front of wheel house on aft bridge deck at first, and then, they were relocated to the wings up to Tsushima.
Probably it comes from the report which Mikasa's captain had submitted after the battle of Yellow Sea. But the report was merely his wish,
***
As to the location of these 2.5pdr(47mm) guns, please refer the article below.