Tokyo rainy-season apartment care: damp and mould

During Tokyo's rainy season, start with the problem you have. If the room is already cool but feels damp, look for a way to remove moisture without making it much colder. If it's hot and damp, cooling comes first. Wet laundry needs its own drying space and airflow.

梅雨 (tsuyu) means the rainy season. The apartment's air conditioner, ventilation and laundry equipment can help with different parts of it. Report a persistent musty smell, water stains or recurring damp early so the apartment manager can investigate.

Choose a setting for the room you have

The 除湿 (joshitsu) or ドライ (dorai) button removes moisture, but it can also make a cool room colder. Daikin's rainy-season guidance explains why the type of dry mode matters.

A weak-cooling dry mode lowers the air temperature while removing moisture. It may stop when the room becomes cool, even if the room still feels damp. A reheat system cools the air to remove moisture, then warms it back towards room temperature. If your unit has this option, it can remove moisture without cooling the room as much. Check the manual for the available modes and how to select them.

For a hot room, use cooling to lower the temperature. Once the room is comfortable, you can check whether a dry setting would help with any remaining dampness. The summer cooling guide explains the controls and what to do if the bedroom stays too hot.

A small temperature-and-humidity meter can help describe a recurring problem. Put it where you spend time, away from direct sunlight or the air outlet, and note the reading with the time and equipment settings. Send those details to the apartment manager if the recommended settings aren't helping.

Find the ventilation controls

Ask which bathroom and room ventilation systems should stay on, and how to use them after bathing or cooking. Look for 換気 (kanki, ventilation) and 24時間換気 (nijūyo-jikan kanki, 24-hour ventilation), but check the panel instructions because one control may manage several functions.

Keep the intended air paths clear. Don't cover a vent with luggage or turn a system off permanently because its sound is unfamiliar. If a fan seems unusually loud, stops working or doesn't remove steam as expected, report it with a photograph of the controls.

Open windows when the weather and building instructions allow. Avoid letting rain enter, follow the building's security instructions and consider whether outdoor air is actually helping the room dry. Close windows as instructed when using cooling or dehumidification.

Make space for a load to dry

Plan laundry around the drying space, not just the washing machine's capacity. A full drum may produce more clothes than your bathroom rail or airer can hold with space between them. Two smaller loads can be easier to dry than one crowded rack.

Look for a bathroom control marked 衣類乾燥 (irui kansō, clothes drying) or 乾燥 (kansō, drying). Check that the equipment supports laundry drying, that the rail is supplied and secure, and what its load limit is.

The door and air inlet matter as well as the setting. TOTO's TYB3111G manual, for example, tells users to close the bathroom window while keeping the air inlet open. If there is no inlet, it calls for a small gap at the door instead. It also says to drain the bath or cover it, because steam from bathwater slows drying. Those are instructions for the models in that manual; use your own model's directions. A shut door and a blocked inlet aren't the same setup as a shut door with air still coming in.

If you use an indoor airer, keep it out of doorways and escape routes. Don't hang wet items from curtain rails, sprinklers or fixtures that aren't intended to carry them. Check garments before storing them, especially thicker seams and waistbands that can stay damp after the rest feels dry.

The laundry guide explains the washer's Japanese labels and how to compare the apartment's drying options with a coin laundry. Having an alternative nearby is useful when several rainy days coincide with work or travel.

Look after bedding and closed storage

Follow the care instructions for the supplied futon or mattress. Ask how it should be aired, whether there is an indoor stand and whether the building permits anything on the balcony. Don't put bedding over a rail without permission or leave it where wind could carry it away.

Avoid packing clothes tightly against a damp wall. Store items only once dry, and leave room for air to circulate where the furniture arrangement allows. Ask the apartment manager before moving a heavy wardrobe or bed.

Moisture-absorbing containers may be useful for a cupboard if used according to their labels, but they don't replace the room's ventilation or a repair. Keep them stable and away from children and pets, and follow the product's disposal instructions when full.

If the same wall, floor edge or cupboard keeps getting damp, send photographs and a description of the pattern. Tell the manager about water stains, dripping or a change after heavy rain. Don't assume the cause is simply that you forgot to open a door.

If you need a separate dehumidifier

Ask the apartment manager whether one is available. Before fitting a continuous-drain hose, get their approval for the setup and follow the equipment instructions. Keep the hose clear of walkways and secure it as directed; don't improvise a route where it could come loose.

If mould has already appeared

Photograph it and contact the company you're renting from, especially on walls, supplied bedding or furniture. Ask what cleaning is appropriate for that material and whether someone needs to inspect the source of moisture. Report recurring or widespread mould rather than repeatedly treating the visible patch.

Don't spray bathroom mould remover on fabric or leather. Kabi Killer's FAQ explicitly excludes fabrics, and its product directions list use and safety conditions. Follow the exact product label on approved surfaces; don't mix it with other cleaners or copy a universal spray-and-wipe recipe.

Ask before sending supplied bedding for professional cleaning or disposing of it. Keep the inspection and cleaning instructions in writing. If you have health concerns related to the damp or cleaning products, contact a medical professional rather than experimenting with stronger treatment.

Keep the routine small enough to use

After a shower, use the ventilation arrangement you've been shown. After laundry, check that the thick items have dried before putting them away. When you notice repeated condensation or a smell in storage, record it and ask for help.

Keep the photos and maintenance replies together until the room is drying normally again.