15 Yokoyama Kenji, Yokoyama Mannen, Ichiaki Hisako, Yokoyama Shintaro, Nagashima Tatsuharu, Nagashima Hideo, Ichiaki Itsuju, Yokoyama Miyoshi all signed this flag in Nagasaki Japan prior to Nagashima Tatsuharu departing for war, possibly in 1944 but perhaps earlier. It was signed by possibly family (Nagashima Hideo, or Hideo Nagashima as we would say in the West) and/or coworkers, as there are multiple references to the Mitsubishi Electrics plant in Nagasaki where it is presumed he worked.
16 On the left reading sideways, it says "serving your country with death".
17 the lines on the farthest right read, "celebration to your war departure, Yokoyama Kenji"
18 The lines near the center going vertically read, "be the first man to get to the enemy" and is signed by Ichiako Hisako.
19 The lines running diagonally say "waiting for your achievement in Nagasaki" and "whimsical man of Mitsubishi", the latter being signed by Yokoyama Miyoshi.
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22 Reverse of this picture is on the right, with translation.
23 This reads "627 at the Northern Manchurian border".
24 This is a part of the Confucian temple in Harbin, Manchuria.
25 The writing reads, "Showa 14th year (1939) Garapan City Division Veterans 14th bayonet fencing practice meeting". This would be a Japanese unit in Saipan, prior to the outbreak of hostilities. Entirely possible the soldiers in this picture are related or the same as the soldiers in the other pictures, who had earlier in the 30's been stationed in Manchuria.
26 This is the Confucian temple in Harbin Manchuria, soldier may have toured a bit while on duty during the invasion of Manchuria which began in 1931 and ended in 1939. Google "Mukden incident".
27 Reverse of picture on the right, with translation.
28 This reads, "627 at the Northern Manchurian border with Sergeant Kami__no". 627 was the unit number.
29 The signs read, "Dawn in Asia" and "First in Kankou", possibly representing the Manchurian invasion.