Well, it's self-published and author explained why she couldn't draw more (cut pages?). Situation is similar to Haruzo's Touko-san can't take care of the house-series, intended to be one but you never know. She's probably also busy (she's currently running another yuri series in Comic Exe which is bimonthly), and it looks like this book is her first doujinshi. You could even say she's inexperienced about how to handle a story/series since she only drew illustrations before. Apparently she'll participate in C93 but as a KanColle booth, so chances are low that we'll get a sequel book this year.