Shinobi Quartet includes
-Very enjoyable characters such as the headstrong (and growing phyicaly strong) heroine and here ninja "acquaintances", as they go thru character development you learn about the stories behind each character, all the meanwhile see them grow strong.
-The story is the format of a master and servant but with the twist of a female master being fought over by her runner upper of being her "right-hand man" ( all having different personalities).
-The story mood is funny at one time and heart racing at the next. Making it quite enjoyable.
-Ah, and it has romance as for a nice touch. Reverse Harem ( ͡° ͜ʖ ͡°) that you can't hate (a full range of them too )