This hotel was a pretty good value for the money, but they try so hard to be a boutique hotel that it was not as relxed and comfortable as we would have liked. We arrived an hour before the official check out time and they would not let us checkin. They did take the bags up to the room before we came back, which was a classy touch you don't often see in budget hotels. The location is nice as it's right beside the river. Although the hotel is very close to the JR station, it's tucked away on a sidestreet and not very easy to find. The staff are nice in a hipster sort of way. The room was nice. The breakfast is served in a French restaurant downstairs. It was a little expensive at 1,200 yen and again, really trying to hard to be a "french" restaurant. It was nice, however, to eat breakfast next to the river and people watch by the bridge.

Apart from the attractive pics on their website we chose the Flex due to how its location fitted in with our itinerary. Our route was an am start from Tokyo so arrival was around 3pm which fitted in anyway with their published check in times. With only a 2nt stay planned our idea was to follow a fellow TA recommendation to go to Myijima island that late afternoon (possible sunsets over the Tori gate). On paper the location looked just across from the station so this would fit in with checking in and then walking back to the station for a bit of sightseeing to make the most of that day.
Flex Hotel theme is modernist particularly over the communal areas, Londoners will know the South Bank exposed concrete look. The rooms have a nod at white minimalist which is reflected even in our pics. However don't expect high quality fittings and finishes, when you get close it looks like a teenage student of architecture has been in control and taken a can of white paint to all the surfaces of the previous existing furniture and surfaces. The other half couldn't get on with the ceiling to floor column “design statement” that is in the way of the window and room either. The chairs are of a primary school size and the bathroom is like a cabin from a caravan too.
We originally requested the superior room but as there were no non smoking rooms left accepted a standard A room. Don't get me wrong the room was quiet, the bed was ok and for the price Y9k it was reasonable. They also offer a buffet breakfast for Y1.2k each which was not bad too and you don't have to reserve it in advance.
However contrary to our map perspective it is more like a 10-15min walk from the station. So you could commit to a taxi from the station to other hotels if they offer a better overall deal and then catch the street car back to the station and still achieve what we did on that day. (Would confirm that Hotel Active is just around the corner from a tram stop, the entrance looked very nice, but that doesn't mean the rooms are of course, and best of luck as we couldn't navigate their Japanese only website.)
We did enjoy the late afternoon on Miyajima island even though the waters were out and the gate was exposed. But be aware this island does seem to be totally given over to the day tripper and providing endless souvenir shops rather than a tranquil cultural centre. We then spent the second day at the Peace Park and the museums, this was well worth the several hours that went by, emotionally tiring but cannot emphasise how much rewarding, so we didn't try and fit anything else in that day other than having a walk around the shopping centre and a meal in the early evening.
Overall if you are aware of the limitations that we judged above it is still worth considering Hotel Flex as an option for a brief stay in Hiroshima.

Shared a double room with a friend at around 7500 yen for a saturday night. A great hotel for seeing the sights of Hiroshima. The area is very peaceful, considering how central it is. Roughly 5 - 10 minutes walk from Hiroshima Station with great views over the city and river. Roughly 15 - 20 minutes walk from places such as the Memorial Museum and A-Bomb Dome, and an equal distance from streets like Nagarekawa - a prominent area for nightlife.
The hotel itself is very sleek and modern and there is a quaint little cafe in reception, though we didn't sample the food. The rooms are on the small size but perfectly adequate for their use. Couldn't fault the cleanliness in either our room, bathroom, or throughout the hotel. The staff really didn't speak much english, but were friendly enough when we required their help.

My Partner and I spent three nights at the Flex Hotel in Hiroshima . We booked into a twin room, and like most rooms we had in Japan the twin room seem to be the better options . the twin beds were big enough to sleep two persons , and it then gives you an option of having your luggage on the other bed . Having seen a double room here we were happy to be in a twim room. We found the staff at the Flex very helpful and if the person we spoke to was not so good with their English then they got someone who could help us. The view from our room over the river was very nice . I really enjoyed staying in this hotel. Within walking distance of the A Bomb Dome and Peace Park. Hiroshima was indeed my favourite city to visit in Japan