A city at night

• 夜(よる) night
• の possessive particle [associates "street" with "night"]
• 街(まち) town; street

In the dim gloom, something white floats into view

• 薄暗(うすくら)がり dim light; twilight
• 白(しろ)く white [白い (white) + く (adverbial form)]
• 浮(う)かぶ float; emerge

Hydrangeas sway gently

• 紫陽花(あじさい) hydrangea
• の possessive particle [associates "flower" with "hydrangea"]
• 花(はな) flower
• が subject marker
• 揺(ゆ)れて swaying [揺(ゆ)れる (to sway; to shake) in て-form, indicating an ongoing action]

The kindness you gave me is still so strong even now; It’s right here

• あなたが you [あなた (you) + が (subject marker)]
• くれた gave [くれる (to give to the speaker or in-group) in past tense]
• 優(やさ)しさ kindness; gentleness [from 優(やさ)しい (gentle; kind) + nominalizing suffix さ]
• が subject marker
• 今(いま)も even now [今(いま) (now) + も (also)]
• こんなに this much
• ここに here
• あって existing [ある (to exist; to be) in て-form, linking to the next idea]

The words and feelings I never told you

• あなたに to you [あなた (you) + に (indicates direction or target)]
• 言(い)えなかった could not say [言(い)う (to say) in potential negative past tense]
• 言葉(ことば) words; language
• や and; or [indicates a non-exhaustive list]
• 思(おも)い thoughts; feelings
• が subject marker

Are now warming someone else

• 他(ほか)の someone else's; other [他(ほか) (other) + の (associative particle)]
• 誰(だれ)か someone
• を object marker
• 温(あたた)めています warming [温(あたた)める (to warm; to heat) in polite continuous form]

In this world where you were born

• あなたが you [あなた (you) + が (subject marker)]
• 生(う)まれた born [生(う)まれる (to be born) in past tense]
• この this
• 世界(せかい) world
• には in; as for [に (location or context particle) + は (contrast or emphasis)]

Beautiful flowers bloom in profusion

• 綺麗(きれい)な beautiful; pretty
• 花(はな) flower
• が subject marker
• 咲(さ)き乱(みだ)れてる blooming profusely [咲(さ)き乱(みだ)れる (to bloom profusely) in colloquial contraction of ている form]

No matter how lovely those flowers may be

• どんなに no matter how
• 綺麗(きれい)な beautiful; pretty
• 花(はな) flower
• だとしても even if [だ (copula) + として (assuming) + も (even)]

You will never return again

• あなたは as for you [あなた (you) + は (topic marker)]
• もう no longer; already
• 二度(にど)と never again
• 帰(かえ)ってこない will not return [帰(かえ)ってくる (to return; to come back) in negative present tense]

If only I’d said, ‘They’re so beautiful,’

• 綺麗(きれい)だね it’s beautiful, isn’t it [綺麗(きれい) (beautiful; pretty) + だ (copula) + ね (seeking agreement or softening tone)]
• って quoting particle [used to indicate direct or indirect speech]

I wish I’d told you properly

• ちゃんと properly; clearly
• 言(い)えば if I had said [言(い)う (to say) in conditional ば-form]
• よかった it would have been good [よい (good) in past form]
• な ending particle [expressing reflection or emotion]

Again this year, on this street corner

• 今年(ことし)も this year as well [今年(ことし) (this year) + も (also)]
• この this
• 街角(まちかど) street corner
• に at; in [indicates location]

The flowers you once nurtured

• あなたが you [あなた (you) + が (subject marker)]
• 育(そだ)ててた raised; nurtured [育(そだ)てる (to raise; to nurture) in colloquial contraction of ていた form]
• 花(はな) flower
• が subject marker

The reason I find them so beautiful

• こんなに this much
• 綺麗(きれい)だ is beautiful [綺麗(きれい) (beautiful; pretty) + だ (copula)]
• と思(おも)う I think [思(おも)う (to think)]
• のは as for the fact that [の (nominalizing particle) + は (topic marker)]

Is because I believe you were right there with them

• あなたが you [あなた (you) + が (subject marker)]
• そこに there [そこ (there) + に (location particle)]
• いてくれていた were there for me [いる (to be) + て-form + くれる (to do for the speaker’s benefit) in past progressive form]
• からだ because [から (indicating reason) + だ (copula)]
• と思(おも)います I think [思(おも)う (to think) in polite form]

In this world where you were born

• あなたが you [あなた (you) + が (subject marker)]
• 生(う)まれた born [生(う)まれる (to be born) in past tense]
• この this
• 世界(せかい) world
• には in; as for [に (location or context particle) + は (contrast or emphasis)]

Beautiful flowers are blossoming everywhere

• 綺麗(きれい)な beautiful; pretty
• 花(はな) flower
• が subject marker
• 咲(さ)き乱(みだ)れてる blooming profusely [咲(さ)き乱(みだ)れる (to bloom profusely) in colloquial contraction of ている form]

No matter how gloriously they bloom

• どんなに no matter how
• 綺麗(きれい)な beautiful; pretty
• 花(はな) flower
• だとしても even if [だ (copula) + として (assuming) + も (even)]

You will never return again

• あなたは as for you [あなた (you) + は (topic marker)]
• もう no longer; already
• 二度(にど)と never again
• 帰(かえ)ってこない will not return [帰(かえ)ってくる (to return; to come back) in negative present tense]

In this world where you were born

• あなたが you [あなた (you) + が (subject marker)]
• 生(う)まれた born [生(う)まれる (to be born) in past tense]
• この this
• 世界(せかい) world
• には in; as for [に (location or context particle) + は (contrast or emphasis)]

White butterflies flutter softly

• 白(しろ)い white
• 蝶々(ちょうちょう) butterfly
• が subject marker
• ひらひらと fluttering; lightly [onomatopoeia for fluttering motion, often of leaves or wings]

Dancing joyfully in the dazzling light, just like that day

• 眩(まばゆ)い dazzling; radiant
• 光(ひかり) light
• の中(なか)で in [の (possessive particle) + 中(なか) (inside) + で (location of action)]
• あの日(ひ)のように like that day [あの日(ひ) (that day) + の (possessive particle) + ように (as; like)]
• 楽(たの)しそう looking joyful [楽(たの)し (fun; joy) + そう (appears to be)]
• 舞(ま)っています dancing [舞(ま)う (to dance; flutter) in polite continuous form]

In the August sky you once gazed upon

• 八月(はちがつ) August
• あなたが you [あなた (you) + が (subject marker)]
• 見(み)ていた were looking at [見(み)る (to see; to look) in past progressive form]
• 空(から) sky
• に in [location particle]

Beautiful fireworks soar once again

• 綺麗(きれい)な beautiful
• 花火(はなび) fireworks
• が subject marker
• また again
• 舞(ま)い上(あ)がり rise; soar [舞(ま)い上(あ)がる (to soar) in stem form, often used in descriptions]

Even in such a beautiful world

• こんなに this much
• 綺麗(きれい)な beautiful
• 世界(せかい) world
• に in [location particle]
• いても even though being [いる (to be) in て-form + も (even if)]

I find myself searching for what’s missing

• 私(わたし)は as for me [私(わたし) (I) + は (topic marker)]
• 足(た)りない insufficient; lacking [足(た)りる (to suffice) in negative form]
• もの things
• を object marker
• 探(さが)してしまう end up searching for [探(さが)す (to search) in てしまう form, implying an unintended or regrettable action]

No matter how beautiful the world may be

• どんなに no matter how
• 綺麗(きれい)な beautiful
• 世界(せかい) world
• に in [location particle]
• いても even though being [いる (to be) in て-form + も (even if)]

One day, these fragile lives will come to an end

• いつかは someday [いつか (someday) + は (contrast marker)]
• 果(は)てゆく will come to an end [果てる (to end) in continuative form with ゆく (indicating progression or change)]
• 儚(はかな)き fleeting [classical or poetic form of 儚(はかな)い (ephemeral; fleeting)]
• 命 life