こじあけて comes from こじあける, meaning to force or pry something open, often with effort. In the song, the singer uses cold water to “force himself open” from drowsiness, creating a vivid image of abruptly waking up and pushing forward.
This is a goodbye song that refuses to be sad about it. The singer opens with a promise, 君を忘れない [I won't forget you], and then heads straight down a winding road anyway. He knows the days of くすぐり合って転げた日 [the day we tickled each other and tumbled over] are gone for good, but what he sees ahead is a future louder and busier than he ever imagined. The whole chorus hangs on one small idea: just the sound of the words 「愛してる」 ["I love you"] made him feel he could be strong.
The details are what make it. He wrote a letter with dirty hands, spilling over with feeling, then asked her to throw it away straight after. Who hasn't done that? He pries his sleepy eyes open with cold water, and life rushes past like he's being blown along. My favourite line is the one where he pretends to be a devil and turns a song he tore apart into 花びら [petals] dancing in the spring wind, which is about as Spitz as an image gets. By the end he's decided he could get through life whether he cheats a little or plays it straight, and he just hopes to run into her again いつかまた この場所で [someday, here in this same place].
Spitz is a Japanese rock band formed in Tokyo in 1987 by four art school students: Masamune Kusano on vocals and guitar, Tetsuya Miwa on lead guitar, Akihiro Tamura on bass and Tatsuo Sakiyama on drums.
They released their first single, "Hibari no Kokoro", in 1991. The single "Robinson" (1995) sold more than 1.6 million copies, "Cherry" (1996) more than a million, and the 1995 album Hachimitsu topped the Oricon chart and won Best Album at the Japan Record Awards.