About the title, I've seen a lot of people write it as "Regress of Progress" and others as "Regress or Progress". My conclusion after looking around was that Mr. Children had a tour named "Regress or Progress" and that the confusion was probably coming from that. For the fans that didn't know, Nino and Domoto Tsuyoshi worked on this song together.
Kanji:
僕の心の欠片を集めて つなげた
その先には 一体何が見える
ねぇ、教えてくれないか
無駄に過ごし 自分をごまかしてる
体にはもう抱くことは出来ないのかな
輝いた 時がかすんでる
君を求めすぎたせいで もう一人で歌えない
愛してると 胸打つ度 君も街もゆがんで見えた
悔しいけど 傷つき灰になった僕を
痛くも強くもある優しさで 包み込む
君のすべてがいまだ恋しいだなんて馬鹿だな
今年も雪が降るかなって言ってた部屋も
今はすごく広くて冷たい
君がいるばずの僕の隣には
最後にくれた癒せない孤独だけ
寒くて足がかじかんで 歩けないよ
寒くて走れないよ
二人だけで 二人だけでよかったんだ
それさえあれば呼吸が出来る
大丈夫だって言い聞かせた夜を
また一人泳ぐ 涙をかわして
Romanji:
Boku no kokoro no kakera wo atsumete tsunageta
Sono saki ni wa Ittai nani ga mieru
Nee, oshiete kurenai ka
Muda ni sugoshi Jibun wo gamakashiteru
Karada ni wa mou daku koto wa dekinai no kana
Kagayaita toki ga kasunderu
Kimi wo motomesugita sei de Mou hitori de utaenai
Aishiteru to mune utsu tabi Kimi mo machi mo yagande mieta
Kuyashii kedo Kizutsuki hai ni natta boku wo
Itaku mo tsuyoku mo aru yasashiisa de Tsutsumi komu
Kimi no subete ga imada koishii da nante baka da na
Kotoshi mo yuki ga mieru kana tte itteta heya mo
Ima wa sugoku hirokute tsumetai
Kimi ga iru hazu no boku no tonari ni wa
Saigo ni kureta iyasenai kodoku dake
Samukute ashi ga kajikande Arukenai yo
Samukute hashirenai yo
Futari dake de futari dake de yokattanda
Sore sae areba kokyuu ga dekiru
Daijoubu da tte iikikaseta yoru wo
Mata hitori oyogu Namida wo kawashite
English:
You gathered the pieces of my heart and put them together
Just what is it that you can see from them
Come on, can't you tell me?
Passing my time idly, trying to fool myself
I wonder if my body won't be able to hold you anymore
The time that used to shine is growing hazy
Because I wanted you so much, I can't sing alone anymore
Every time I was moved by your "I love you"s, both you and the city appeared distorted
It's frustrating, but after I'd been hurt and turned to ashes
I was wrapped up in a gentleness that was both painful and strong
I guess it's stupid to say everything about you is still dear to me
Even the room where you asked if we'd see snow again this year
It feels incredibly vast and cold now
In the space next to me where you should be
There is only the incurable loneliness that you gave me in the end
It's so cold, my legs have gone numb and I can't walk
It's so cold, I can't run
With just the two of us It was good with just the two of us
If I only had that, I could breathe
The nights where you persuaded me it was alright
I'm treading alone in them again, fighting off the tears
<3