I also tried to look up for the surname “Tajitsu” in the Pioneros database (
https://dji.jomm.jp/es/search.php0, which provides data from Japanese immigrants to Peru. It shows a person called Nariharu Tajitsu (田実成治). Considering that this database contains many discrepancies between the reading and the original Japanese spelling (data is compiled from the records kept by the Diplomatic Archives of the Ministry of Foreign Affairs of Japan, and the reading is added later by university students), I assume that this is indeed your relative (成治 is strikingly similar to 誠治, and both can be read as “Seiji”). His origin is given as Fukushima prefecture, which I cannot account for, but the database gives his birthday as March 1st, 1898 (which is accurate), and states that he arrived in Peru in November 27th, 1918, aboard the Anyo-maru (which matches the information from Shigeji Ikeda’s books). He was sent to the Esquivel farm upon arrival. I wasn’t able to track anything further in the Peruvian sources.