[Help!] Who (Meiko) and Who (Luka) during in Colorful x Sexy

I got this romaji from: http://www.youtube.com/watch?v=ScDaxLScKf8
It's not that 100% accurate. I mean of who sings this line and this line. My hearing isn't the feat for this (romaji), so i'm here asking for a help on the proper labeling on who sing this particular line or words. Also, if you can provide an english translation as well, I would be more glad:

koyubi o karama se tara [luka]
otona no yoru hajimaru [luka]
terasa re ta raito no shita de [luka]
kuchibiru kara koboreochi ta toiki [luka]
irodo rarete ku futari no sekai ga [luka]

honto ni hoshii mono wa [meiko]
minna ga kureru shisen [meiko]
tada mitsume rare teru dake de [meiko]
mune ga gyutto shimetsuke rare teiku [meiko]
suteji no ue de hajima ru yume [meiko]

dore dake no suki o tsutae tara iino ka na
kimochi wa ima aka? ao? shiro?
aimai da ne
kagayai te i tai
itsumademo aishi te moraeru you ni

itsumo [both] kokoni kita tokiha [meiko] sabishii kao demo [luka]
futari de kae temiserukara

itsuka yume ha same te shimau to [luka]
shit te iru yo dakedo ima dake [meiko]
yureru kokoro dakishime te i tai yo
subete o sutete mo
karafuru na kanjou afure teiku

dore dake no suki o tsutae tara iino ka na?
kimochi wa ima aka? ao? shiro?
aimai da ne
kagayai te i tai
itsumademo aishi te moraeru you ni

itsumo [both] kokoni kita toki ha [meiko] futari de matte ru [luka]
minna de ai o sodateyo u

itsuka [both] mata ki ta toki ni ha [meiko] sabishii kao toka [luka]
sasenai karafuru x sekushii