The prefix ま, coming from the kanji 真（ま） (true), is attached to words in Japanese to express that something is ‘completely’, ‘exactly’, ‘genuinely’ (A). Depending on the word that follows 真（ま）, several different conjugation patterns will be used. This conjugation depends on which column the first kana of the word after 真（ま）comes from. ま comes from the ま, み, む, め, も column, for example.
When linked with a ま column, or な column word, 真（ま） will become 真（ま）ん.

• この猫（ねこ）は真（ま）ん丸（まる）していてかわいい。
  This cat is completely circular and cute. (This cat is so fat that it is cute)
• 真（ま）ん中（なか）にある本（ほん）をとってください。
  Please take the book in the middle.

When linked with a か column, さ column, or しゃ sound word, 真（ま） will become 真（ま）っ.

• 体（からだ）が真（ま）っ赤（か）になるくらい お風呂（ふろ）が熱（あつ）かった。
  The bath was so hot that my body went completely red.
• サルが木（き）から真（ま）っ逆（さか）さまに落（お）ちた。
  The monkey fell completely upside down from the tree.
• 道（みち）が雪（ゆき）で真（ま）っ白（しろ）になった。
  The road turned completely white with snow.

When linked with a は column, 真（ま） will become 真（ま）っ, and the first kana of the following word will change to a ‘P’ sound.

• ちょっと、何（なん）で真（ま）っ裸（ぱだか）なの？
  Wait, why are you completely naked?
• 真（ま）っ昼間（ぴるま）からこんな話（はな）をするの？
  You are going to talk about this in the middle of the day? (Are you seriously going to talk about something like this in the middle of the day?)