personal grudge

Kyūjitai form of 私鉄 (“private railway”)

Isle of Man (an island and Crown dependency of the United Kingdom in the Irish Sea)

a mandrill

walkman (any personal cassette player)

monthly

(slang) a sexually promiscuous woman, a slut / (derogatory, slang) a young woman who acts in lax and sexually suggestive manner

yes man (a person who always agrees with his employer or superior)

拳万: pinky swearing (linking little fingers to confirm a promise)

one-on-one fight / (by extension) one-on-one competition or contest