Again!!, Orange Recommendations
Orange and Again has traits that can be thought provoking. This is because of a supernatural element that revolves around time that influences with both series' story. The main characters realize that they can influence events from the past, present, and future with this supernatural phenomenon. There's a great deal of focus on characters as they use their knowledge and resolves to make important decisions in both series. Expect characterization, story building, and relationship dynamics. There is also romance present in both series although Orange has more of a shoujo vibe while Again!! has more of a shounen feel.
First, they both talk about time traveling. Second, they both talk about the clearing of ones regrets. (through the use of time travel--of them or letters)