I’ve read the phrase “ni no mai wa gomen da” before (二の舞はごめんだ). This hails from the Japanese expression, “ni no mai o enjiru” (二の舞を演じる), which basically reads “dancing the same dance twice” and means “making the same mistake twice”. So, the top phrase means, “Not gonna make the same mistake.”
The image at the top of the post is of Shiro Amada, the main protagonist of “Mobile Suit Gundam: 08th MS Team”. Before the “proper” show starts, Shiro Amada was an Earth Federation soldier serving on a space colony that saw its entire civilian population wiped out by poison gas during the Republic of Zeon’s first strikes against the Federation. Shiro was saved because of his military issue spacesuit, but was helpless to save anyone else. While this was not shown in the anime itself, it was represented in an animated cut-scene in a Gundam video game I once played and enjoyed.
During the first episode, Shiro sorties in a crude prototype of a zero-G construction vehicle that has been weaponized for combat, a “Ball” (that looked like one, except with two cannons stuck on the top) that was considered unable to fight any mobile suit (the big humanoid, man-piloted robots) in one on one combat. He sortied from a transport shuttle, risking his own life, to save a survivor of a Federation mobile suit squad with a damaged machine.
In making his sortie, he said to him self, “Side 2 no ni no mai wa gomen da!” In other words, he wouldn’t allow a repeat of Side 2, which wasn’t really a mistake so much as a circumstance: his own helplessness while others died.
As fate would have it, he and the enemy mobile suit essentially had a double K.O. and both pilots, himself and a beautiful enemy soldier, were forced to cooperate to survive aboard a Federation shipwreck until they could send out a signal and attract rescue from their respective sides. The soldier Shiro saved returned to rescue him the moment his mobile suit was sufficiently repaired, and was transferred to the squad Shiro became the leader of: the 08th MS Team, as we call it in English. (The Japanese word “shoutai” (小隊), which can be ID’d when used in a military context, almost always reads as “platoon”.)
Anyway, I use this example from an anime I know well to show how “ni no mai” is used. Remember, it’s “mai” not “mae” (forward/ front). “Mai” is for dance, here. – J