In every issue of Ribon magazine, the most popular manga will feature title pages printed in full color. Back in the 70s and through the 90s, it was quite common for a serialized manga to contain three (or more) color pages each month, and readers would look forward to the beautiful full-color title pages as well as the manga pages in color. Because these color pages wouldn't be included in the tankōbon releases, they were a great incentive for readers to purchase the magazine every month, and many fans cut out and kept these color pages even if they threw away the magazines after a while.
Unlike shōnen magazines, in which color pages are scarse and generally do not indicate much about the popularity of a certain series, the color pages in shōjo magazines are an important measure of both a series' popularity with readers, and how much the magazine wants to appeal and promote a series to its readers. When a series used to be allotted color pages, but suddenly loses them, fans call this "color-ochi" — to be "dropped" from color pages. Another thing that can happen is a series losing the number of color pages, usually going from three to just one. These factors let the readers know of the ups and downs of a series' popularity, and is of great interest to fans.* Sometimes, a series will have at least one color page every month until its anime wraps up, after which it will go through "color-ochi"; in this case, the color pages say more about the appearance of popularity rather than actual popularity with readers.
* You can liken it to the series order in Weekly Shonen Jump, which is said to be an almost direct mirror of the weekly popularity rankings, and is endlessly scrutinized by dedicated readers.
Tokimeki did not go through "color-ochi" even once during its serialization. The Ranze arc would generally feature three color pages every month, sometimes more, and the Narumi arc was the same. Things started changing towards the last half of the Aira arc, however; from chapter 16 onwards, Tokiemki would only occasionally have three color pages. This indicates very clearly that Tokimeki was no longer a top series in the reader polls.
What's interesting about Ikeno's color work, I feel, is that she would very often use two of the three color pages for manga, and only one page for the title page. I've noticed that this is in contrast to many of her contemporary Ribon artists through the 80s and 90s, who preferred to use two pages (a spread) as the title page. I feel this shows Ikeno often wanted to use as many pages as possible to tell her story.
On these pages, I've collected scans of the color title pages and colored manga pages in my collection which have not been reproduced elsewhere, i.e. either in the Romantic Album fanbook or the exhibition catalogue. I'm doing this because I believe Ikeno's color art is some of the most beautiful in the history of shōjo manga and should be preserved for prosterity. If you are at all interested in manga art, please seek out the two aforementioned books — especially the exhibition catalogue is well worth the money!