Not only that, but he has a Kickstarter
https://www.muevo.jp/campaigns/1493
EDIT: in fact, why don't I earn my keep around here for once and mention what's on offer.
0 yen:
Thank-you message from Seiji
Subscription to Seiji email newsletter
2000 yen:
All of the above plus:
Early access to Seiji's first music video
4000 yen:
All of the above plus:
Original "nuigurumi" hand towel, an "uchiwa" fan personally signed by Seiji, and a sticker.
7000 yen:
All of the above plus:
A personally signed A3-size Seiji photo
High-quality JPG photos/outtakes
13000 yen:
All of the above plus:
Original Seiji t-shirt
PDF of the fashion design sketches for Seiji's outfits
A handwritten New Year's message from Seiji in January 2019
20000 yen:
Everything from the 13000 yen tier plus:
Invitation to a special limited concert on 7/28
20000 yen:
Everything from the 13000 yen tier plus:
Seiji will record a comment video for you personally, and send you a signed/commented autograph board
30000 yen:
Everything from the 13000 yen tier plus:
Invitation to dinner and karaoke with Seiji on 7/29
30000 yen:
Everything from the 13000 yen tier plus:
Seiji will sing a song where your name is substituted into the lyrics, and give you a CD-R of the recording
Seiji will record you a video message when he does the recording for the song
50000 yen:
Everything from the 13000 yen tier plus:
An invitation to a "secret studio live and fan meeting" on 7/14, where they'll take your picture with Seiji and you can request a song for him to sing
500000 yen (!!):
Your own made-to-order version of Seiji's kimono
5000 yen:
Just the ticket to the 7/28 concert without all the other stuff.
So if you ever wanted Seiji to sing a song for
you personally, now's your chance