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  • Streaming + Download

    Includes unlimited streaming via the free Bandcamp app, plus high-quality download in MP3, FLAC and more.
    Purchasable with gift card

      ¥100 JPY  or more


  • Cassette + Digital Album

    The following track are only recorded on the cassette!
    ・Sieg This Love (prod by Tsudio Studio)
    ・Slow Wave (prod by HiRO .JP)

    We use shipping services to keep shipping costs down, and it may take up to six months from the time of shipment to arrive. If you do not receive it after six months, please contact us.

    Please note, that there is no tracking service for shipments outside Japan.
    If you wish, it is possible to change the shipping method to EMS with tracking service by adding 3000 yen to the shipping fee. Please contact us after purchase.

    Includes unlimited streaming of Opto5​​​:​​​Mandark via the free Bandcamp app, plus high-quality download in MP3, FLAC and more.
    ships out within 14 days

      ¥1,500 JPY or more 



二人腰かけていた 部屋の窓辺にひとり
余り突然すぎて あなたの影が私を苦しませる


少しずつ感じていた あなたとのすれ違い
言い忘れた言葉が 心の影で私を苦しませる




from Opto5​​​​​​​:​​​​​​​Mandark, released June 7, 2023
Track 1:
Produced, Words and Music by HiRO .JP
Vocal by Mandark


all rights reserved



光学 Japan

Tsudio Studio、SNJO 、HiRO.JPの3名による音楽プロデューサー・ユニット<光学>


Koh-Gaku (光学) are a producer team consisted of Tsudio Studio, SNJO and HiRO.JP.

Koh-Gaku features different guest vocalists on every releases.
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