I went looking for an erasable way to write in a contrasting color today, and ended up with two.
I got some red leads for my mechanical pencils. This is the backup plan, because this has been known to work since around the time I was born, probably even earlier.
I remembered some tolerable erasable ballpoints from years ago, and looked for them (hoping for red or green or at least blue), and couldn’t find them (at Office Depot). However, I stumbled across the Pilot pen given in the title.
The line is finer than I like (but it’s described as “fine”, so it’s as described). The pens started writing a bit roughly, but after a few inches of line they wrote well enough. They’re scratchy, not smooth—but that’s why I don’t like “fine” pens, so there may not really be anything wrong with them in that regard.  The red and the black ink are quite intense, certainly good enough.
Which brings us to the erasing.
The erasing is nothing short of miraculous. I have never before had anything, including a pencil, that erased as cleanly as this pen does. Furthermore, the eraser doesn’t leave crumbs behind (it sounds like it erases by heating the ink by friction). After erasing, the space on the paper looks absolutely pristine.
This won’t become my favorite pen in general, and mostly I’m happy enough living without erasing. But for special cases, like marking up documents or correcting homework or exams, where being able to erase mistakes cleanly is important, this will become my tool of choice.
(The packaging suggests that you NOT use this pen for legal documents. Sounds like good advice to me.)