Title: Cutie Honey Tennyo Densetsu (キューティーハニー天女伝説) / Cutie Honey, the legend of an angel / Cutie Honey '21 (it) / 甜心戰士 (tw, hk)
Original run: 2001-08-21·28 ~ 2001-09-25, 2001-10-09 ~ 2003-07-29
Magazine: Weekly Manga Action (WEEKLY漫画アクション)
Publisher: Futabasha (双葉社)
Volumes: 9
Volumes:

2001-12-19; Cutie Honey Tennyo Densetsu #1, Action Comics, Futabasha, ISBN-10: 4-575-82636-7, ISBN-13: 978-4575826364, http://www.futabasha.co.jp/?isbn=4-575-82636-7 http://www.amazon.co.jp/dp/4575826367

2002-04-12; Cutie Honey Tennyo Densetsu #2, Action Comics, Futabasha, ISBN-10: 4-575-82672-3, ISBN-13: 978-4575826722, http://www.futabasha.co.jp/?isbn=4-575-82672-3 http://www.amazon.co.jp/dp/4575826723

2002-07-12; Cutie Honey Tennyo Densetsu #3, Action Comics, Futabasha, ISBN-10: 4-575-82706-1, ISBN-13: 978-4575827064, http://www.futabasha.co.jp/?isbn=4-575-82706-1 http://www.amazon.co.jp/dp/4575827061

2002-09-28; Cutie Honey Tennyo Densetsu #4, Action Comics, Futabasha, ISBN-10: 4-575-82743-6, ISBN-13: 978-4575827439, http://www.futabasha.co.jp/?isbn=4-575-82743-6 http://www.amazon.co.jp/dp/4575827436

2002-12-23; Cutie Honey Tennyo Densetsu #5, Action Comics, Futabasha, ISBN-10: 4-575-82781-9, ISBN-13: 978-4575827811, http://www.futabasha.co.jp/?isbn=4-575-82781-9 http://www.amazon.co.jp/dp/4575827819

2003-03-28; Cutie Honey Tennyo Densetsu #6, Action Comics, Futabasha, ISBN-10: 4-575-82823-8, ISBN-13: 978-4575828238, http://www.futabasha.co.jp/?isbn=4-575-82823-8 http://www.amazon.co.jp/dp/4575828238

2003-07-28; Cutie Honey Tennyo Densetsu #7, Action Comics, Futabasha, ISBN-10: 4-575-82857-2, ISBN-13: 978-4575828573, http://www.futabasha.co.jp/?isbn=4-575-82857-2 http://www.amazon.co.jp/dp/4575828572

2003-11-12; Cutie Honey Tennyo Densetsu #8, Action Comics, Futabasha, ISBN-10: 4-575-82900-5, ISBN-13: 978-4575829006, http://www.futabasha.co.jp/?isbn=4-575-82900-5 http://www.amazon.co.jp/dp/4575829005

2004-03-12; Cutie Honey Tennyo Densetsu #9, Action Comics, Futabasha, ISBN-10: 4-575-82953-6, ISBN-13: 978-4575829532, http://www.futabasha.co.jp/?isbn=4-575-82953-6 http://www.amazon.co.jp/dp/4575829536

Specials:

2008-01-01 (2001-12-25); Cutie Honey Tennyo Densetsu Special: Tennyo Korin Hen (キューティーハニー天女伝説スペシャル　天女降臨編); saita mook COMICS!, Seven & I Publishing Co. (セブン＆アイ出版); http://funuke01.cocolog-nifty.com/blog/2008/01/2008_2813.html (Includes Tantei Jimusho H.G)

2008-01-01 (2001-12-25); Cutie Honey Tennyo Densetsu Special: Ketto! Panther Majo Gundan Hen (キューティーハニー天女伝説スペシャル　決闘！パンサー魔女軍団編);saita mook COMICS!, Seven & I Publishing Co. (セブン＆アイ出版); http://funuke01.cocolog-nifty.com/blog/2008/01/2008_6b57.html

(it)

2004-07-23; Cutie Honey '21 #1, D/visual, ISBN-13: 9784902751017, http://www.d-world.jp/dv/product_info.php?products_id=36

2004-10-15; Cutie Honey '21 #2, D/visual, ISBN-13: 9784902751062, http://inkiostro.net/osCommerce/product_info.php/manufacturers_id/19/products_id/509

2004-12-17; Cutie Honey '21 #3, D/visual, ISBN-13: 9784902751123, http://inkiostro.net/osCommerce/product_info.php/manufacturers_id/19/products_id/510

2005-02-18; Cutie Honey '21 #4, D/visual, ISBN-13: 9784902751185, http://inkiostro.net/osCommerce/product_info.php/manufacturers_id/19/products_id/511

2005-04-15; Cutie Honey '21 #5, D/visual, ISBN-13: 9784902751192, http://inkiostro.net/osCommerce/product_info.php/manufacturers_id/19/products_id/512

2005-04-29; Cutie Honey '21 #6, D/visual, ISBN-13: 9784902751208, http://inkiostro.net/osCommerce/product_info.php/manufacturers_id/19/products_id/987

2005-06-30; Cutie Honey '21 #7, D/visual, ISBN-13: 9784902751215, http://inkiostro.net/osCommerce/product_info.php/manufacturers_id/19/products_id/513

2005-09-08; Cutie Honey '21 #8, D/visual, ISBN-13: 9784902751222, http://inkiostro.net/osCommerce/product_info.php/products_id/514

2005-10-26; Cutie Honey '21 #9, D/visual, ISBN-13: 9784902751239, http://inkiostro.net/osCommerce/product_info.php/products_id/515

(tw, hk)

2005-11-10; Cutie Honey The Legend of an Angel #1, d/books, d/visual taipei, ISBN-10： 9787184118

2006-02-01; Cutie Honey The Legend of an Angel #2, d/books, d/visual taipei, ISBN-10： 9867184130

2006-05-02; Cutie Honey The Legend of an Angel #3, d/books, d/visual taipei, ISBN-10： 9867184149

2006-09-03; Cutie Honey The Legend of an Angel #4, d/books, d/visual taipei, ISBN-10： 9867184157

2006-09-15; Cutie Honey The Legend of an Angel #5, d/books, d/visual taipei, ISBN-10： 9867184203

2006-12-05; Cutie Honey The Legend of an Angel #6, d/books, d/visual taipei, ISBN-10： 9867184211

2007-05-05; Cutie Honey The Legend of an Angel #7, d/books, d/visual taipei, ISBN-10： 986718422X

2007-07-02; Cutie Honey The Legend of an Angel #8, d/books, d/visual taipei, ISBN-10： 9867184238

2007-08-25; Cutie Honey The Legend of an Angel #9, d/books, d/visual taipei, ISBN-10： 9867184246

Links:
http://en.wikipedia.org/wiki/Cutie_Honey_Tennyo_Densetsu
http://www.mazingerz.com/HONEY/TENNYO.html
http://www.asahi-net.or.jp/~wx5h-ktb/gofo/honey/honeyten.html
http://www.mangadb.it/showmanga.php?idmanga=427
http://www.sinet.it/baroncelli/manga/honey.htm
http://www.ebookjapan.jp/shop/nagaigo/news.asp (2008-02-23)
http://www.k3.dion.ne.jp/~h-kazu/dynamic/shinkan/shinkan.htm
http://www.ilmondodelfumetto.it/store/home.php?cat=1242
http://www.feliceshopping.com/index.php?cPath=24_54_38
http://www.fumetto-online.it/it/ricerca_editore.php?EDITORE=D-VISUAL&COLLANA=CUTEY%20HONEY%2021%20%28m9%29
http://www.manganet.it/autori.asp?Extra=GO+NAGAI

I didn't know about this one. What it's about?

I don't really know more than what's on Wikipedia. You should ask the Italian members of this forum that may have read it. Also, I'm sure there are some Italian forums as well that could give us more details of the story.