Today I will learn 10 new words.

かけがえのない: irreplaceable 

気が置けない: easy to get along with

気心: disposition 

打ち明ける: confess

察する: sense

同い年: same age

連中: group 

呼び捨て: to be called without honorifics

身の上: circumstances

徹する: devote oneself to