It was announced by his nephew:
This feels weird as I was reading his interviews and stuff just some months ago. Once again it remains me death comes unannounced. This is very sad news. I pray his family will be able to recover from this trial. According to fans on twitter it seems Iuchi san’s last job was Rilu Rilu Fairiru episode 35. Fairilu’s director is Pretty Rhythm’s director Hishida Masakazu, so it seems they worked together until the end.
Source: Iuchi san worked on Mazinger Z, Yamato and 999. Then he regularly worked on Sunrise shows from the 80’s until now. He was the director of Wataru, and also worked on Keroro, Aikatsu! or Gundam Build Fighters. He also wrote a LN for Wataru.
When Pretty Rhythm director directed his first show, Onmyou Taisenki, Iuchi san worked on it and helped him. Pretty Rhythm director also worked on Keroro.
While they already knew each other for many years before that, as Pretty Rhythm director joined Sunrise and worked on Wataru under him. it seems to be around when they where working on Keroro together that they started sharing ideas for the Pretty Rhythm anime project.
Pretty Rhythm Aurora Dream and all three seasons aired on TV Tokyo on Saturdays at 10am. This is the timeslot Keroro used to air in just before AD started, and like if a bridge was created across both shows, there’s a lot of staff who worked on Keroro who also worked on Aurora Dream. Kyougoku Takahiko, Kondo Nobuhiro, Tokumoto Yoshinobu, and many others. This may be the case for Sekita Osamu as well.
There’s many anime directing styles existing. You can say Tomino san style and Ryousuke san style, and Iuchi san himself was taught by Tomino san, but probably one could say “Iuchi san style” as well. Yamamoto Yusuke, Kondo Nobuhiro who taught Hishida san along with Iuchi san, Furuta Takeshi san, Hishida san who taught Kyougoku Takahito san, they’re all proof of it.
Iuchi san decided many things for Pretty Rhythm. He’s the one who decided on zettai aidoru AI N G and many other plot points or fun things in all three seasons.
The ANN article linked condolences by anime industry people but didn’t translate them, I tried to sum them up along with the other ones I found. There’s also the words from Pretty Rhythm’s director and Pretty Rhythm scriptwriter Tsubota Fumi:
Pretty Rhythm Director Hishida Masakazu:
PR Director switched his twitter avatar to the photo above with Iuchi Shuji, Tsubota Fumi and him. That was the photo for their interview in the Pretty Rhythm All Star Selection book.
“This photo represents my best piece of memory with Iuchi san”
“Iuchi Shuji san, who was my benefactor, my master, my enemy, my rival, my friend, and who wrote scripts on works I was responsible of, passed away on December 15. I can only think of words of gratitude toward him. I think he will rest in peace. Hiro and all the characters made by Iuchi san will keep living on.”
(Many fans including myself noted how what he says, being rivals and friends, is a very important theme developed in Pretty Rhythm like with Mia and Hye In)
“I am sorry for the typos my previous tweets may have had as I am very upset”
“Everyone, please never forget about Burning Sword Breaker”(That’s Iuchi san who thought up the technique and it’s very influenced by techniques in shows he director before like Shining Sword Breaker in Crush Gear Turbo)
I think Iuchi san would be happy if his name got in the twitter trends.
Pretty Rhythm Storywriter Tsubota Fumi:
“He was a really nice person. I don’t know how I considered him, it’s myesterious. He neither felt like a second father living in tokyo(She is from Okayama prefecture) or a master. I really liked him.”
“Iuchi san, please rest in peace. I still have trouble believing it… When I get over there, I’ll bring a bottle of Syrah so we can enjoy it together.”
Pretty Rhythm Scriptwriter Murakami Momoko:
“I just received The Rainbow Live BD box2. I have learned a lot under IUchi san. He was nice and charming, a truly wonderful person. As long as there’s people who keep watching Puririzu Iuchi san’s sparkle will keep shining and won’t disappear.”
“My master Iuchi Shuji passed away. It will be hard to express all of my gratitude with twitter’s limits, so I will only say “thank you””
“My 30 years long friend and great senpai Iuchi Shuji san passed away on December 15. It is very regrettable and sad news.”
“Director Iuchi has passed away. He was still very young, this is very regrettable. I had the chance to work under director Iuchi on Wataru and Granzort. (On Crush Gear as well). When I was starting up Cyber Formula, he also gave me many pointers.”
Kimura Ryuichi (Aikatsu! director):
“Iuchi Shuji san passed away. He even did storyboards for Aikatsu!. My sincere condolences.”
Kyougoku Takahiko (Love Live director, who worked on Pretty Rhythm):
“My great senpai in animation direction Iuchi Shuji san has passed away. I will forever admire him. Thank you very much.”
“I have worked under director Iuchi on Chou Wataru but besides that I didn’t have many opportunities to work with him. However even now I still feel indebted to him and it feels like I will never be able to repay him. “
牟田口裕基 (Animation director on SD gundam Sangokuden):
“I really liked director Iuchi’s works. I pray he will rest in peace”
“Iuchi Shuji san who did the storyboard for episode 13 of Shōnen Ashibe GO! GO! Goma-chan has passed away. He left many wonderful works behind.”
山口仁七(Animator working on Fairiru):
“Iuchi san did many storyboards for Fairilu. When I was a kid I watched Wataru and Granzort, so I was deeply moved when I saw his storyboards for Fairilu. Thank you”
A PR fan did a quick tweet summarizing the PR episodes Iuchi san worked on:
Someone took out from his old shelves the November 97 Animedia, with an interview of Iuchi Shuji san:
I have Mama wa shougaku yon nen sei in my high priority watch list but still haven’t seen it as that’s a subcategory of the watchlist of things I don’t want to watch alone. I guess I’ll just watch it anyway if I have the time.
Edit from May 2017:
The weekend of the 25th February 2017, there was a memorial event for Iuchi Shuji, It was for anime staff persons only, but a lot of fans sent flowers.
Yamamoto Yusuke: “I went to the meeting in commemoration of my master”
Murakami Momoko who worked on Pretty Rhyhm’s scripts: “Thank you for giving me the opportunity to work on Pretty Rhythm”
Tsubota Fumi was there too.
This person worked on Pretty Rhythm, but their twitter don’t mention their actual name so I don’t know who it is.
Yamaguchi Ryota was present too.Maybe others, that’s all the tweets I saw. It’s nice tons of people who worked with him went there, I hope it helped his family with their mourning and made them happy to see how he was appreciated.