At that time in Nigeria, almost all priests were foreign missionaries. Few Africans were being ordained to the priesthood. Tansi was ordained a priest for the Archdiocese of Onitsha at the
Cathedral Basilica of the Most Holy Trinity in Onitsha on 19 December 1937. As Black priests became more common, some followed the lifestyle of the foreign missionaries. Monks and nuns also lived more comfortably than most Nigerians, and some people began looking at taking holy orders as a priest, monk or nun as a way to escape poverty. When he became a parish priest, he lived an austere life in comparison to the priests around him. He built his own home using traditional materials. He would sleep on any bed, even if it was uncomfortable. He would eat even poorer food than what the local people ate, surviving on tiny portions of yam. He went by foot, used bicycles, and sometimes had a motorbike. He also travelled during rainstorms. Nigerian Catholics were not accustomed to this kind of priest. He became popular in the four parishes he served in:
Nnewi,
Dunukofia, Akpu/Ajalli, and his home town Aguleri. He organized programs for the needy, taught people building techniques, and was remembered as being kind. He also stood up against oppression of women within the traditional culture and advised women to fight back against those who would rape or mistreat them. On one occasion, a female parishioner was attacked by a group of males, and she fought back against them. Fr Michael, who was nearby, came on his bicycle and joined with her and fought them until they fled. He then encouraged her to bring the assailants to court, which she did, winning the case against them and forcing them each to pay her four pounds; this case was a milestone in the establishment of women's rights in Nigeria. He was unyielding in confronting vice among his flock. He had a special interest in preparing young women for marriage. With the help of local nuns, the women were taught about Christian marriage and how to care for the children they would have. He would organize the community to place the bride to be in a special home wherein she would be looked after until she got married. He would not allow men to see their brides before they got married, and if the groom attempted to go there without Fr. Tansi's permission, he could be penalized. He also had a women's group organized, who would enforce disciplines on their own members to avoid premarital sex and deter
abortion. He was strict with students who failed to work hard at the parish school. He was known to hide near the school; when he saw students coming late, he would emerge from hiding and penalize them. He was remembered for being a perfectionist, which sometimes caused resentment. Later, his experience as a novice monk gave him insight into his earlier methods and caused him to reconsider. He also was opposed to some aspects of the traditional pagan culture in Nigeria. Nigerian pagans had murdered his own mother after claiming she was a witch who had caused mischief. ==Trappist monk==