Unreleased Songs Update (Adding Miyamoto Karin's Section):
Miyamoto Karin
[2017] Pink Moment
[2018] 20sai no Birthday (20歳のBirthday; 20th Birthday)
[2018] LOVE, KISS, NEED, YOU
[2019] Hyoutenka (氷点下; Below Freezing)
[2019] Tamerai (タメライ; Hesitation)
[2019] Chuushajou no Onee-san (駐車場のお姉さん; Parking Lot Lady)
[2019] Wakamono Brand (若者ブランド; Youth Brand)
[2019] Shoujo K (少女K; Girl K)
[2019] "Ochikobore no Garakuta Datte" (「落ちこぼれのガラクタだって」; "Even Scattered Junk")
To add more info:
[2017] Pink Moment (Lyrics, composition: Miyamoto Karin | Arrangement: Ohashi Riko)
[2018] 20sai no Birthday (20歳のBirthday; 20th Birthday) (Lyrics, composition: Miyamoto Karin | Arrangement: Ohashi Riko)
[2018] LOVE, KISS, NEED, YOU (Lyrics, composition: Miyamoto Karin | Arrangement: Ohashi Riko)
[2019] Hyoutenka (氷点下; Below Freezing) (Lyrics, composition: Yamazaki Aoi)
[2019] Chuushajou no Onee-san (駐車場のお姉さん; Parking Lot Lady) (Lyrics, composition: Miyamoto Karin)
I doubt her self-written songs will ever be released officially. At least in their current forms. Rather than something that has real chance to be released, they are more like product of Karin's musing with her new-found hobby of song-writing and music composing. The company allowed Karin to do whatever she wants in her BD event, so she just put them in the setlist.
But then, she got Ohashi Riko to make arrangements for them, so..
Also, LOVE, KISS, NEED, YOU is actually pretty decent.
Anyway, for those who don't know, Karin had a solo live tour last month, touring around Zepp halls in Tokyo, Namba and Nagoya. In it she performed seven new songs, including one self-written song (the parking-lady one). One of them has been released digitally and is available on iTunes, Recochoku and mora.
Doushite Bokura ni wa Yaruki ga Nai no ka
Check it out. It's really nice