What is the meaning of "Itsukushimi" in Japanese?

"Itsukushimi"  towa? ...#1

"Itsukushimi" wa bukkyoo kara kiteimasu. ...#2

Anata ga anata no paatonaa ya nakama ya subete no soozoobutsu no

shiawase o negau toki, "Itsukushimi" no imi o rikaidekirudeshoo. ...#3

"Ashita" toiu Nakajima Miyuki san no kyoku o shookaishitai to omoimasu. ...4

Kono kyoku no naka ni konna fureezu ga arimasu. ...#5

Moshimo "Ashita" watashitachi ga nanimokamo nakushite

tada no kokoro shika motanai yaseta neko ni nattemo  

moshimo "Ashita" anata no tame nanno toku mo nakutemo

ieru nara sonotoki 

"Ai" o kikasete. ...#6

#1 ...What is the meaning of "Itsukushimi" in Japanese?

#2 ..."Itsukushi" is originated from Buddhism.

#3 ...If you wish a happiness of your partner, companion,

       and all creation, you will understand the meaning of “Itsukushimi”.

#4 ...I would like to introduce a song titled “Ashita” by Nakajima Miyuki .

#5 ... There is a phrase in this song (in below).

#6... "If we lose everything tomorrow,

         and even if we become skinny cats who have only ordinary "heart",

         and even if I will not benefit for you,

         and if you can tell me something more,

         let me listen a  word,  "love".