It's a homemade banjo-like instrument that can also be played with a bow.There's a popping noise in the middle of the song. Don't worry about it.
自作のバンジョー的な楽器です。弓で弾くこともあります。曲の途中でパチッというノイズが入っています。気にするな。

Recording Equipment：
Homemade 2-Stringed Banjo,
Gibson LesPaul Studio,
Fender Jazzbass,
Behringer V-AMP PRO,
Maxon Auto Filter AF-F1,
Yamaha QY300,

Bandcamp

Homemade 2-Stringed Banjo in D open

Manga artist, Bedroom musician, Cat owner.
Books: "The Mysterious Frog Princess", "The Mysterious Mummy Girl", "37564 Academy", "Girls' Alliance", "True Horror Stories", "Graveyard Classroom", "Crab Woman"
Music: "Young Antonio's Alien Experience", Inun-do, "Attack of the Killer Hamster", Monofonus Press (USA)
Band: Mankos (2003-)

CD: "Antonio Young Man's Alien Experience" Inundo
Cassette Tape: "Attack of the Killer Hamster" Monofonus Press(USA)
Book: "Mysterious Frog Princess""Mysterious Mummy Girl""37564 (Minagoroshi) Academy""Girls' Alliance""True Horrible Stories (Blue Comics BLACK BUNKO - Mysterious Horror Complete Works)""Graveyard Classroom"and "Crab Girl"

Homemade 2-Stringed Banjo in D open

Mori Kanda